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suggestions for --> Topic for next week: Difference between due to/ because of

The expression "due to" can only be used to MODIFY NOUN ONLY.

LINK Unlike the premiums for auto insurance, the premiums for personal property coverage are not affected by the frequency of claims, but if the insurance company is able to prove excessive loss due to owner negligence, it may decline to renew the policy.

LINK This is a good example to discuss.

In California, a lack of genetic variation in the Argentine ant has allowed the species to spread widely; due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits the spread of this species in its native Argentina.

(A) due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits

(B) due to its being so genetically similar the ant considers all its fellows to be a close relative and thus does not engage in the kind of fierce intercolony struggles that limit

(C) because it is so genetically similar, the ant considers all its fellows to be a close relative and thus does not engage in the kind of fierce intercolony struggles that limits

(D) because they are so genetically similar to one another, the ants consider all their fellows to be close relatives and thus do not engage in the kind of fierce intercolony struggles that limit

(E) because of being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits

And the verbal chat is underway! Come join us for the 90 most exciting minutes in the GMAT verbal world. We'll be here until 9:30 PST/10:00 IST.

Chat Transcript - 5/24/2017

Q: Can you point out the difference between 'due to' and 'because of' ?
A: Here, I have two examples:
1) The picnic was canceled due to rain.
2) Souvik’s incredible GMAT score was due to his hard work.
Basically, you’ll want to ask yourself: what does the "due to _____" phrase modify?
1) The picnic was canceled due to rain. --> what does "due to rain" modify?
"due to rain" doesn’t modify "rain", yes -- it modifies the cancelation.
Trouble is, the word "cancelation" doesn’t appear -- it just says "was canceled". That’s a verb.
And "due to" can’t modify a verb or verb phrase -- just nouns

Q: I read on egmat that always replace due to by 'caused by'. If it sounds right then fine. Is this approach wrong?
A: Yeah, but I’ve found that a lot of people tell me that "The picnic was canceled caused by rain" sounds OK, and "Souvik’s success on the GMAT was caused by his hard work" sound bad. So it doesn’t work for everybody.

Q: So 'Souvik’s success on the GMAT was because of his hard work' is not correct?
A: Souvik’s incredible GMAT score was due to his hard work. --> what does "due to his hard work" modify?

Q: Does it modify Souvik’s action or work?
A: No, "due to his hard work" does not modify "work." The "due to _____" phrase indicates some sort of causality. You want to ask yourself what is affected by the "due to ____" phrase. In this case, it’s the GMAT score that’s "caused" or "affected by" or "due to" Souvik’s hard work.
Bottom line on "due to": the phrase "due to _______" must logically modify a noun, not a verb phrase.

Q: One confusion. If we state a reason for something, we use because of. So, in this question can’t we say the reason for his score is his hard work. I agree that His score is caused by his hard work but reasoning concept has confused me now.
A: The weird thing about "due to" and "because of" (and "caused by", I suppose) is that they all mean basically the same thing. But the distinction is grammatical. The only thing that the GMAT really seems to test is the fact that "due to" can NEVER modify a verb or a verb phrase -- just a noun.
This sentence "makes sense", but it’s wrong: "The game was postponed due to rain."

Q: I am still not clear. How to identify due to is modifying noun or verb phrase?
A: "due to rain" -- what happens "due to rain"? What is being modified by "due to rain"? You wouldn’t say that "the game is due to rain." The thing that "due to rain" modifies is "was postponed" -- it’s the postponing that happens "due to rain." And that can’t work: "was postponed" is a verb phrase. That’s really all. You’ll never see anything other than a noun after "due to" anyway, so that’s a non-issue. And I wouldn’t overthink "because of" -- I’ve never seen an official GMAT question that requires you to think too deeply about "because of", at least not that I can think of.

Q: Can you explain the basic rules to follow in a comparison based question?
A: OK, some generic thoughts on comparisons.
They should be really straightforward, and there should be really good rules for them. But there sometimes aren’t.
Some things have super straightforward rules: "like" or "unlike," for example: "Like the poetry of Bruce Willis, Chuck Norris is flowery and pretty." Easy to see the problem there... I hope.

Q: Aren’t we comparing poetry to Chuck Norris?
A: Exactly. And it really doesn’t make a whole lot of sense to compare poetry to Chuck Norris.
That’s sort of the basic level of GMAT comparisons: "like" or "unlike" or "-ings" or "-eds" -- the two things being compared need to make logical sense.

Q: The main problem comes when we have ellipsis. Can you explain?
A: "Like the poetry of The Rock, an intelligent, charismatic, muscle-bound mutant who is toying with a bid for the United States presidency in 2020, that of Chuck Norris is flowery and pretty."
You can compare The Rock to Chuck Norris, or you can compare the poetry to the poetry -- but you can’t really compare a man to poetry.
So they can be devious about sticking a bunch of garbage in the middle of the comparison to make it hard to see what’s up -- but the fundamental principle is no different, even with that rant in the middle. It’s about being strict and literal about what’s being compared. It’s fairly easy to spot when there are obvious "key words" such as "like" or "unlike" or an "-ing" modifier. Trickier when they get more subtle.

Q: Currently 26 billion barrels a year, world consumption of oil is rising at a rate of 2 percent annually.
A. world consumption of oil is rising at a rate of
B. the world is consuming oil at an increasing rate of
C. the world’s oil is being consumed at the increasing rate of
D. the rise in the rate of the world’s oil consumption is
E. oil is consumed by the world at an increasing rate of

A: OK, so I’m getting a bunch of different answers -- but let’s focus on the comparison
Currently 26 billion barrels a year, __________
What sort of thing would actually make sense in the blank? "the rise"?, "oil", in general?
It wouldn’t make sense to say that "oil" is currently 26 billion barrels a year.
So here’s the key concept on comparisons of all sorts: you have to be strict and literal. You can’t compare poetry to Chuck Norris, and you couldn’t say that "oil... is 26 billion barrels a year."
In that sense, modifiers and comparisons are awfully similar on the GMAT -- it’s really the same logic that you’re employing in both cases, whether you’re dealing with "like" and "unlike" or "in contrast to" (comparisons) or "-ing" or "-ed" modifiers... or something like "currently 26 billion barrels..."

Q: Please explain use of As. Is it used before noun?
A: Long thread on like and as, if that’s what you’re asking about, SVSI. But "as" can be used in hundreds of different idioms, so there’s no single rule on "as". https://gmatclub.com/forum/i-have-strug ... l#p1850401

Q: Many airline carriers are attempting to increase profitability while keeping overhead low by offering, in terms of flights, an equal amount as last year, doing so by using larger planes that fly more efficiently.

A. an equal amount as last year,doing so by
B. the same number offered last year
C. an equal amount offered last year and
D. the same number as last year but
E. an equal number as were offered last year,

A: The key is figuring out -- for each answer choice -- the exact, literal comparison that the sentence is making.
(and there’s more to this one than just the comparison, btw -- parallelism, countable vs. non-countable)
based on just countable vs. non-countable, A and C are gone. "Amount of flights" doesn’t work.
I think the difference between (B) and (D) is pretty subtle, but there’s a really good reason to eliminate it.
So when you’re down to two on SC, you can always do this: find EVERYTHING that differs between the two answer choices. And then ask yourself what EACH difference does to the meaning of the sentence.
"offered" vs. "as" -- any thoughts?

(B) ends up being redundant. Is (B) totally horrible because of the redundancy? I guess that’s debatable, but it’s definitely not as good as (D) in that sense.

Let’s talk about the "but". Why do we need it?
Without but, the sentence really isn’t clear:
Many airline carriers are attempting to increase profitability while keeping overhead low by offering, in terms of flights, an equal amount as last year, doing so by using larger planes that fly more efficiently.

So we’re increasing profitability by offering the same number of flights, using larger planes that fly more efficiently? There’s a contrast there -- and the "but using larger planes..." makes that contrast clearer. Hard question, but (B) is a little bit redundant, and it doesn’t present the meaning as clearly as (D) does, because (B) doesn’t show the contrast using "but" in this case. Really subtle. Hard.

Q: From where shud we do SC? Is EGMAT enough?
A: Many of you have heard me say this dozens of times already, but the GMAT spends between $1500 and $3000 developing each test question. E-GMAT would go out of business if they tried to do that. Even the best test-prep companies can’t compete -- so for practice, official questions are always the best. You can learn topics from e-GMAT or MGMAT or GMAT Club, but official questions still win when you’re practicing.

Suggested topic for coming section [BOLDFACE].

A product that represents a clear technological advance over competing products can generally command a high price. Surprisingly, perhaps, the strategy to maximize overall profits from a new product is to charge less than the maximum price the market will bear. Many companies charge the maximum possible price for such a product, because they want to make as much profit as they can and technological advances tend to be quickly surpassed. The drawback is that large profits on the new product give competitors an incentive to quickly develop a product to match the rival product's capabilities

In the argument above, the two portions in boldface play which of the following roles?

(A) The first is the position that the argument advocates; the second presents grounds for rejecting an alternate position.
(B) The first is the position that the argument advocates; the second is an alternative position that the argument rejects.
(C) The first presents a strategy for achieving a certain goal, the second presents a drawback to that strategy.
(D) The first presents a strategy for achieving a certain goal, the second presents grounds for preferring a different goal.
(E) The first presents a strategy that, according to the argument, is ineffective; the second presents a way of improving the effectiveness of that strategy.

LINK

Boldface sounds like a great topic. I will also probably suggest inference questions! They (in my mind) are VERY similar.

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Boldfaced questions and inference questions sound great! If any of you have specific (preferably official) questions you'd like to cover, feel free to add them to the thread here, and we'll pick one or two of the best exemplars for Wednesday's chat.

GMATNinja Perhaps we could discuss the question as below for the coming verbal chat. [LINK]

Scientists typically do their most creative work before the age of forty. It is commonly thought that this happens because aging by itself brings about a loss of creative capacity. However, studies show that of scientists who produce highly creative work beyond the age of forty, a disproportionately large number entered their field at an older age than is usual. Since by the age of forty the large majority of scientists have been working in their field for at least fifteen years, the studies’ finding strongly suggests that the real reason why scientists over forty rarely produce highly creative work is not that they have aged but rather that scientists over forty have generally spent too long in their field.

In the argument given, the two portions in boldface play which of the following roles?

(A) The first is a claim, the accuracy of which is at issue in the argument; the second is a conclusion drawn on the basis of that claim.

(B) The first is an objection that has been raised against a position defended in the argument; the second is that position.

(C) The first is evidence that has been used to support an explanation that the argument challenges; the second is that explanation.

(D) The first is evidence that has been used to support an explanation that the argument challenges; the second is a competing explanation that the argument favors.

(E) The first provides evidence to support an explanation that the argument favors; the second is that explanation.

Chat Transcript - 5/31/2017

Q: I have a question specific to Sentence Correction Strategy...My Verbal is pretty Weak(26-32) and i have recently started achieving good accuracy in CR and RC (RC was decent always) but my SC is still pretty low (<50%). As suggested by a lot of experts here in GMATCLUB, i studied from MGMAT SC and Aristotle (still learning Idioms List). But kind of a little demotivated..What do u suggest..solving 2000 questions (and analyzing) will help or re-reading the material again. I have only 45 days left.

A: The link I just posted probably isn’t exactly right for you, but there’s some stuff in there that might apply. Basically, I wonder if your brain is getting "logjammed" with all of the rules and idioms, and maybe you’re having a hard time separating the important stuff from the less-important stuff. MGMAT covers a TON of rules. It’s a great book. It can overstuff your brain, and then make it harder to actually look for the right things in the questions. Not sure if that applies to you, but it might. And I’ll have plenty of wisecracks about idioms in this week’s topic of the week -- so keep an eye on the SC subforum.

Q: In the past i have improved on sc and cr part, but i am not able to improve on the rc part, please suggest

A: Yeah I think SC is faster to improve. There are a few rules and logical impositions that you can learn quickly. You shouldn’t look at rules a lot but try to decipher the acceptable and non acceptable forms of GMAT sentences by reviewing carefully tons of official problems. What I sometimes tell my students is that the books contain 150 rules and 300 idioms (or something like that -- I’m making those numbers up, obviously), but the GMAT SC really stresses about 15 rules.
I think if you can truly master parallelism and comparisons (which I think is a type of parallelism) a majority of your battle is over. Add modifiers and pronouns to the list. But yeah: four topics will take care of most of the battle. From there, it’s mostly about understanding the differences in meaning between answer choices.

Q: How many questions we might get from parallelism and comparisons?

A: Not really sure what that means but I’d strongly advice against predicting what the test wants to do. Sure there are certain traps that you should get used to but I honestly think the test is way more straightforward than people make it out to be. Especially the whole concept of ’think like a test taker’ - I never understood that. I’d rather say ’think like a well prepared candidate.
Basic SC technique: cross out everything you can based on definite, absolute grammar rules. Things you’re sure about. Subject-verb, that kind of thing. Then, compare remaining pairs of answer choices and figure out everything that differs between the two sentences -- and see if you can figure out what’s different between them when you look at those differences strictly and literally.
Also ’meaning’ is often touted as this really complicated silver bullet for SC. It is really not. More often than not the meaning will boil down to modifier placements.

Q: How to improve in generally related to the meaning of the sentence? Some times we non-native struggle

A: There’s nothing horribly complicated or technical there. Just try to figure out how a few words impact the meaning. And yes, it’s often things like modifier placements, or changing the form of a word so that it tweaks the meaning a little bit. But there are no formulas for this stuff -- it’s just being literal and logical.

Q: Have a doubt related to your topic on RC strategy. If the RC passage is way too dense and after reading the first/second paragraph, we are still unsure about its role/structure because it is too difficult to comprehend. What should we do? Continue reading or re-read, glancing quickly?

A: I think what you’re asking is related to something I was about to say about SC: sometimes, figuring out the difference in meaning between two SC answer choices is very strongly related to how good you are at deciphering the precise meaning of a sentence... and that’s basically just a fundamental reading skill. The same is true if you’re reading an RC passage and can’t figure out what’s going on: that’s when you might just be hitting the limits of your reading skill. Sure, maybe a better breakfast or an extra cup of coffee will help you focus and read better in that moment, but that’s not always enough. So sometimes there’s a long-run need to just get more exposure to good, difficult reading in English.
It’s not glamorous, but for some people who have mastered every technique out there but STILL can’t get to their ideal level on verbal, the issue is just a lack of reading skill. And that can take time to develop, unfortunately.

Q: I found out that most of the RC fall within particular sentence from the passage that exactly match with the question stem.

A: That might be true of either very easy RC or non-official RC questions. If you’re seeing questions of any real sophistication (say, 600+), you’ll have to understand the passage fairly thoroughly to get most of the questions right.

Q: Could you suggest any "hard stuff" material to read?

A: Try hard official RCs. This could be a stretch but op-eds are sometimes useful. there are a couple of links at the end of this article: https://gmatclub.com/forum/experts-topi ... 41004.html -- bb and carcass have started a couple of good threads with reading recommendations. I personally just like the NY Times and the Economist, but that’s just me. Academic journals are also really good if there’s something that interests you -- generally, the level of language in academic journals is absolutely brutal. Or at least it can be.

Q: Need help on inference questions

A: I think I’m a little bit of a purist when it comes to CR: you don’t want to overcomplicate them. Inferences in particular. The dictionary definition of "inference" probably says something about unstated facts. An inference is something that wasn’t said directly in the passage. Technically speaking. But I don’t think that’s useful on the GMAT, to be honest.
Basically, when you see an inference question, your mindset should be: I’m going to find the four answer choices that aren’t true based on the passage. The one that remains must be the right answer. An "inference" can be anything from a very very simple restatement of a fact in the passage, or a very complicated conclusion that you draw from the facts in the passage. Or anywhere in between.
Bottom line: don’t overthink inferences! Find the four that aren’t true based on the passage, and that’s it.

Q: Need help on Boldface questions

A: The tricky thing about BF CR is that they’re kind of messing with our expectations of what boldface is supposed to do. The natural instinct is to read these BF CR and feel like the thing in bold is important -- a conclusion or something. But it probably isn’t. Best way to structure your thinking is to try to completely ignore the bold type at first. Just see if you can find the conclusion. And then see if you can figure out how everything else in the passage fits in with that conclusion. Basically, you just want to understand the logical structure of the argument. Ignore the bold at first. (And incidentally, this is exactly the same recommendation as I would give for strengthen/weaken/assumption questions: find the conclusion. You can’t possibly weaken or strengthen a passage until you’re 100% clear about the conclusion and how the author arrived at that conclusion.) Once you’ve found the conclusion and you understand the structure of the argument in these BF SOBs, then it’s a whole lot easier to figure out how the boldfaced stuff fits with the conclusion and the rest of the argument. Just don’t get tricked into over-obsessing over the boldfaced right away. Figure out the structure first, then go from there.
To be fair: the other really hard thing about BF is the way the answer choices are phrased. But there’s no magic bullet for getting better at understanding those, other than just practicing a lot.
From Souvik: Yeah one thing that has helped me with bold faced question is to identify the conclusion. If the conslusion is one of the boldfaced statements that becomes an easy way to boil it down to a couple of options. Sometimes the bold face are supporting evidences so you can rule out quickly all the answer choices that says the bold faces statements are conclusions. So basically getting a somewhat clear understanding of the framework of the argument helps a LOT. (but beware - sometimes there are multiple conclusions in bold faced arguments - I guess the GMAT term is intermediate conclusion)

Q: Need help on Strengthen and Weaken questions

A: But large profits on the mew product will give competitors a strong incentive to quickly match the new product’s capabilities. If you tweak a couple of words here or there, you can get into trouble. "X is a good course of action" ≠"X is the best course of action" ≠ "X is the only course of action" ≠ "X is the recommended course of action". Just an example: one word can completely change everything. Just an example: one word can completely change everything. But logically? I don’t think that there’s much going on with strengthen and weaken questions. You intuitively know what the words "strengthen" or "weaken" mean. If you’re missing those questions, it’s almost certainly because A) you’re not clear about the structure of the argument, particularly the exact conclusion, or B) you’re misreading something, perhaps in a very, very tiny way. But again, I’m a little bit of a purist here: you can learn all the logical structures you want, but if you misread something by a little bit, you can get in trouble. CR is much more about precision of reading than it is about complicated logic. And strengthen/weaken questions are some of the best examples of that. Not much advanced logic required, but precise reading is key.

Q: A product that represents a clear technological advance over competing products can generally command a high price. Because technological advances tend to be quickly surpassed and companies want to make large profits while they still can, many companies charge the greatest price the market will bear when they have such a product. But large profits on the mew product will give competitors a strong incentive to quickly match the new product’s capabilities. Consequently, the strategy to maximize overall profit from a new product is to charge less than the greatest possible price.

In the argument above, the two portions in boldface play which of the following roles?

A. The first is an assumption that forms the basis for a course of action that the argument criticizes; the second presents the course of action endorsed by the argument.
B. The first is a consideration raised to explain the appeal of a certain strategy; the second is a consideration raised to call into question the wisdom of adopting that strategy.
C. The first is an assumption that has been used to justify a certain strategy; the second is a consideration that is used to cast doubt on that assumption.
D. The first is a consideration raised in support of a strategy the argument endorses; the second presents grounds in support of that consideration.
E. The first is a consideration raised to show that adopting a certain strategy is unlikely to achieve the intended effect; the second is presented to explain the appeal of that strategy.

BF1: technological advances tend to be quickly surpassed
BF2: large profits on the mew product will give competitors a strong incentive to quickly match the new product’s capabilities
Conclusion: Consequently, the strategy to maximize overall profit from a new product is to charge less than the greatest possible price.
A: Not sure that you’d call the 2nd BF a course of action, exactly. So we can get rid of (A)
B: The "strategy" is: "many companies charge the greatest price the market will bear when they have such a product". BF1 is giving you a reason to adopt that strategy: technological advances tend to be quickly surpassed. BF2 tells you why that’s a bad idea: large profits on the new product will give competitors a strong incentive to quickly match the new product’s capabilities. And if BF2 is true, it helps us draw the conclusion: Consequently, the strategy to maximize overall profit from a new product is to charge less than the greatest possible price.
C: As somebody pointed out earlier, BF1 really isn’t an assumption at all. Also hard to see how BF2 casts doubt on an assumption. Perhaps on the strategy to charge as much as possible, but not on an assumption.
D: The conclusion endorses charging LESS than the greatest possible price. The first BF actually supports a different strategy: charging as much as possible.
E: Similar to (D), in some sense: BF1 gives a reason why companies charge as much as possible. So BF1 definitely doesn’t give us a reason why the strategy WON’T achieve its desired effect.

Suggestions for :

Topic of the week: Correct usage of 'being'
Discussion of the week - verbal chat on Wednesday - Meaning v/s grammar

Suggested topic : CR - Evaluate the Argument.

Recommend question to discuss. LINK

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the growth of this herb have discovered that it produces large amounts of histidine, an amino acid that, in test - tube solutions, renders these metals chemically inert. Hence, the herb's high histidine production must be the key feature that allows it to grow in metal-rich soils.

In evaluating the argument, it would be most important to determine which of the following?

(A) Whether the herb can thrive in soil that does not have high concentrations of the toxic metals.
(B) Whether others of the closely related group of plants also produce histidine in large quantities.
(C) Whether the herb's high level of histidine production is associated with an unusually low level of production of some other amino acid
(D) Whether growing the herb in soil with high concentrations of the metals will, over time, reduce their concentrations in the soil.
(E) whether the concentration of histidine in the growing herb declines as the plant approaches maturity

Nice ideas, warriorguy and hazelnut! "Being" is a leading candidate for the very next Topic of the Week -- so please stay tuned.

And please keep the suggestions coming, everybody! Always happy to take requests.

Chat Transcript - 6/7/2017

Q: Can we please start with comparisons first?
A: OK, let’s start with comparisons... and meaning. All at once, because I’d argue that it’s sort-of all the same topic. Sort of.
You’ll see roughly 17 SC questions. And if you’re always using process of elimination, you’ll cross out 68 wrong sentences over the course of your test. (And you should always use process of elimination. Don’t ever fall in love with a verbal answer choice! Find four wrong choices.) I like to say that of those 68 wrong answer choices, roughly half are "mechanical" and half are "non-mechanical." By "mechanical", I mean things that are governed by a clear grammar rule -- cases when you can see a clear, unambiguous error.
Examples of clear, mechanical errors: countable vs. non-countable modifiers, pronouns with no antecedent, subject-verb errors, etc.
Think of that stuff as roughly half of the test. The other half is a whole lot trickier -- "non-mechanical" errors that generally have something to do with subtleties of meaning. Those are much, much harder. But to be fair, I think the line between "mechanical" and "non-mechanical" is blurry sometimes. And comparisons tend to occupy that really blurry space between "mechanical" and "non-mechanical" errors.
This is straightforward, right: "Like LeBron James, Kevin Durant is pretty good at basketball."
Or "Unlike LeBron James, the quality of basketball play by Kevin Durant isn’t quite as good." -- clearly wrong, since you can’t compare LeBron to basketball
So there’s a family of comparisons that, IMO, end up being straightforward, and they "feel mechanical" as a result. "Like" and "unlike" are giving you very, very clear clues.
"in contrast to" would be another obvious one, that basically works the same way as "like" or "unlike"

But here’s the thing: the people who write the GMAT don’t really claim to be testing grammar. It’s a "verbal reasoning" section, not a "grammar and reading" section, right? So they’re more concerned about connecting structure and meaning than anything else -- and comparisons can be a nasty way to see if you’re really dialed into the literal meaning of sentences.
Another example:
1. The debt-GDP ratio of Greece is lower than Japan.
2. The debt-GDP ratio of Greece is lower than that of Japan.
3. The debt-GDP ratio of Greece is lower than that of Japan’s.
#1 is comparing Greece’s debt-GDP ratio to Japan itself, and that makes no sense.
#2 correctly compares "the debt-GDP ratio of Greece to the debt-GDP ratio of Japan"
but #3 gets a little bit more subtly crappy: "the debt-GDP ratio of Greece to the debt-GDP ratio of Japan’s" -- and yeah, you could think of it as "Japan’s... what, exactly?", you could think of it as a bizarre double-possessive or something ("that of" and "Japan’s" both indicate possessiveness)
I’d love to say that there are some magical formulas we can give you for comparisons, but even in the debt-GDP ratio example -- which is actually relatively straightforward -- it’s mostly about thinking strictly and literally about the precise comparison in each sentence, and asking yourself if the comparison actually makes sense

Plants are more efficient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.

A. Plants are more efficient at acquiring carbon than are fungi
B. Plants are more efficient at acquiring carbon than fungi
C. Plants are more efficient than fungi at acquiring carbon
D. Plants, more efficient than fungi at acquiring carbon
E. Plants acquire carbon more efficiently than fungi

Is anybody driving themselves nuts trying to figure out whether "are" is necessary in (A) vs. (B)?
This is interesting and cool -- a lot of my students find this plant/fungi question confusing, because they get stuck on whether you need the "are" or not. and this sentence is not GMAT-correct: "whether... or not" is redundant! But nobody cares in real life.
This is typical GMAT: they’re distracting you with some funny stuff in that "comparison" at the beginning. But guess what? They’re also telling you that it doesn’t matter, because there’s a very clear meaning error in A, B, and E.
A, B, E seem to be saying "fungi, in the form of carbon dioxide..." -- and that doesn’t work
Classic GMAT. If you get too hung up on one thing, you’ll miss the meaning issue that is probably WAY more important, especially in a case like this
and I’d make a similar argument about idioms: if you’re not sure about an idiom, see if you can find other errors, and don’t worry about it.
So bottom line for comparisons: there really aren’t a whole lot of magic structural/grammatical rules that will save you, but if you’re being really strict and literal with the meaning, that’s going to get you a long way.

Q: I understand the meaning issue. Is "more efficiently" grammatically correct?
A: Sure, "more efficiently" would just be an adverb that modifies "acquire" -- so I don’t see anything wrong with that

Q: Many airline carriers are attempting to increase profitability while keeping overhead low by offering, in terms of flights, an equal amount as last year, doing so by using larger planes that fly more efficiently.

A. an equal amount as last year,doing so by
B. the same number offered last year
C. an equal amount offered last year and
D. the same number as last year but
E. an equal number as were offered last year,

I have read in the forum that we can ignore words when the tense is not changing. But here are we allowed to do that? Isn’t there a tense change from offering to offered? Please correct me if I am wrong

A: I get really nervous whenever I hear the phrase "ignore words." I agree that there are moments when you have to TEMPORARILY block out a chunk of the sentence in order to understand what’s going on ("A bag of peaches cost more in Georgia than in Colorado." -- you need to ignore "of peaches" momentarily to see that this is wrong), but I see a lot of overzealous word-skipping. Not sure if you’re doing that here, but the phrase in general makes me nervous. The thing you’re ignoring is likely to affect SOMETHING in the sentence, somewhere.
but yes -- I think it’s clear enough without repeating "as was offered last year"
And that’s the heart of GMAT SC when you’re wondering if something can safely be omitted: is the meaning still clear? Or at least clearer than in the other answer choices?
One last example:
1) Prairie dogs live in colonies of several dozen that often have many puppies as well as a large number of adults.
2) Prairie dogs live in colonies of several dozen prairie dogs that often have many puppies as well as a large number of adults.
3) Prairie dogs live in colonies of several dozen of them that often have many puppies as well as a large number of adults.
In real life: I really don’t like #1. It feels a little bit unclear to me. But it’s correct. In #2, "them" is just ambiguous enough to give us trouble. (Another future topic of the week: pronoun ambiguity isn’t always wrong... but it’s not ideal if you have a better alternative!)
And the difference between #1 and #3 is just the repetition of "prairie dogs". I’d argue that it’s unnecessary, and so would the GMAT. You know in #1 that we’re talking about several dozen prairie dogs -- so there’s no need to repeat.
Again, I don’t love the "sound" of #1, but nobody cares what I think. If we’re analyzing the sentence based on logic and meaning, there’s no need for the repetition in #3.

Q: Few points on pronoun ambiguity
A: A good way to understand pronoun ambiguity is that it is only ambiguous if you could replace both the nouns in question and still make sense.
The best way to understand those nuances is to just solve official questions and understand them. A lot of officially correct answers have ’ambiguous’ pronouns.

Q: As per your experience, pronoun and idioms are not usually deterministic errors.
A: I wouldn’t go that far! Pronouns can definitely be definite errors, and so can idioms. It’s just that pronoun ambiguity isn’t always wrong. If a pronoun has NO reasonable antecedent, it’s definitely wrong...
"Whenever I go to the post office, they overcharge me for stamps."
We know what "they" refers to: post office workers. But it’s still wrong.

Q: Although jogging is known to cause knee injury, it can be avoided if the right pair of jogging shoes is worn.

A) Although jogging is known to cause knee injury, it
B) The fact that jogging is known to cause knee injury
C) Injury to the knee caused by jogging
D) Jogging is known to cause knee injury, although it
E) Jogging is known to injure the knee, which

’it’ is ambiguous in option A because ’it’ can refer to ’jogging’, which is the subject. Although its meaningless to say that jogging can be avoided if the right pair of jogging shoes is worn.

A: actually, the "it" unambiguously refers back to "jogging", since the second clause starts with a pronoun -- that pronoun refers back to the subject of the first sentence. But yeah, the meaning makes no sense. Whenever a sentence has two full clauses -- generally, one independent and one dependent clause, or two independent clauses separated by a semicolon -- then if the second clause starts with a pronoun, that pronoun unambiguously refers back to the subject of the first clause.

Q: How do you best approach/study verbal part of GMAT ? Do it topic by topic such as modifiers, parallelism etc or category by category like RC,CR,SC ? Reason i am asking is i can speak fluent english but don’t remember the actual grammar terms like subject, object, nouns n stuff.

A: OK, so here’s the thing I liked about this question: how much do you need to worry about grammar jargon?
In my opinion: the grammar jargon really doesn’t matter at all. A couple of reasons:
1) the section is called "verbal reasoning", not "grammar and reading" -- the GMAT is trying very hard to test your ability to connect structure to meaning on SC. Sure, there’s some grammar involved, but the heart of it is whether you can think strictly and literally about whether a particular sentence adequately and clearly expresses the correct meaning.
2) when you do need to understand grammar, the labels don’t matter. Do you know whether a verb matches its subject? If so, I really don’t care if you know what the term "verb conjugation" means, as long as you can do it correctly.
Verb tenses are one of my favorite examples: as long as you understand what each tense actually DOES, then I don’t care if you know what it’s called. "past progressive perfect tense" -- really not important that you know that term. BUT... if it helps you to have labels for the grammatical structures, that’s totally cool! For some people, the jargon helps them learn the actual grammar and usage. For others, the jargon is torture.
Americans tend to be AWFUL with grammar jargon. We never really learn it as kids. So I don’t use it at all when I teach most Americans, because they’ll run screaming in the opposite direction if I do. But it is really helpful for some people.

Q: Exactly i can tell if a sentence doesn’t feel right by just saying it in my mind. But what should the approach be ?
A: exactly! If that’s how you feel, don’t worry about the labels! But if you’re better at understanding "-ing" nouns because you use the term "gerund", that’s cool.

Q: The moment we see a SC question. What should be the approach?
A: Two simple steps:
1) Cross out anything that contains a DEFINITE error. If you’re certain that, for example, the pronoun has no antecedent, or the subject-verb agreement is wrong, or the parallelism is definitely wrong... then cross it out. But if you’re not CERTAIN, don’t eliminate it just yet. On average, I think you’ll be able to get rid of about half of the answer choices through clear, certain eliminations -- but it obviously varies from question to question.
2) Compare the remaining pairs of answer choices, and see if you can figure out EXACTLY what the differences are. Then think about whether those differences are going to impact the meaning in some way. And that part gets really subtle and tricky
Kind of like that prairie dog example from earlier: when you really think strictly and literally about the differences between those sentences, it’s reasonably clear that the crappy-sounding option #1 was the best of the bunch. So it’s never, ever about "sound." That’s the easiest way to walk right into a trap. Even for native speakers.
I think that a huge percentage of correct GMAT sentences sound like hot garbage. I used to manage a team of writers. Using GMAT SC sentences -- correct ones -- would have gotten them fired, because many of the right answers are wordy, messy, and sound like crap. So keep your ear out of it! "Verbal reasoning", not "ooh, this sounds good."
And now that I’m thinking about it: in a weird way, non-native speakers have a subtle advantage in this regard. Native speakers obviously have more experience with English, but some of them really struggle to be strict and literal and analytical when they read SC sentences. It can be harder for them to "turn their ears off" -- and that’s generally what needs to happen.

Hi GMATNinja,

Can you please explain the correct usage of 'having' and 'having been' in the upcoming Verbal Chat session? I know its quite similar to other 'verb-ing' words but I have rarely seen any correct answer choice having 'having been'. Why is the usage of 'having been' considered incorrect and can you point to any official question having 'having been' in the answer choice?

Hi Vyshak,

I just found something useful from the internet.

Perhaps GMATNinja could help to explain the timeline for the Perfect Participle.

Perfect Participle

[ACTIVE] Having finished my work, I went home.
[PASSIVE] My work having been finished , I went home.

[ACTIVE] Having kept the bird in a cage for so long, Jade wasn't sure it could survive in the wild.
[PASSIVE] The bird, having been kept in a cage for so long, might not survive in the wild.

Extra Example

If we wish to emphasise that one action was before another then we can use a perfect participle (having + past participle):

Having won the match, Susan jumped for joy.
Having realised that you were going to be late, you should have phoned to change your appointment.
Having passed my driving test, I thought I could hire a car.

Having been told the bad news, Susan sat down and cried.
Having been shown into the office, Julia waited for the dentist to arrive.
Having been stung by bees, she has no love of insects.

Useful Link for Passive Voice ([LINK])

Excerpt from Manhattan GMAT Sentence Correction

Having been shown into the office, Julia waited for the dentist to arrive.

CORRECT. The words having been shown are considered a participle, not a working verb. The whole phrase that precedes the comma (.Having been shown into the office functions as a participial phrase modifying the verb waited.

Nonetheless, the words having been shown have verb-like features, and they are strongly analogous to a verb in the past perfect tense and in the passive voice.

The presence of the helping verb to be, here in the form been, puts this in the passive voice. The use of the verb to have, here in the form having, indicates that the action of being shown into the office oc­curred before Julia waited for the dentist. Since this meaning is perfectly logical, the participle having been shown is correct.

Sure, that sounds great, Vyshak and hazelnut -- we've had a few questions on "having been" or "having + past participle", and I think we might have addressed them a little bit in one of the chats, but I'm happy to tackle it again. Would also make a pretty good Topic of the Week for sometime in the future...