GMAT Ninja SC Expert - Ask Me Anything about GMAT SC and Grammar

95. Although some officials noted that using machines for farming in China costs more than traditional hand cultivation, the mechanization of farming in the village of Long Bow doubled the corn yield while the previous year’s costs were cut in half.

(A) mechanization of farming in the village of Long Bow doubled the corn yield while the previous year’s costs were cut in half
(B) mechanization of farming in the village of Long Bow doubled the corn yield while cutting costs to half those of the previous year
(C) mechanization of farming in the village of Long Bow doubled the corn yield as cost were cut to half of the previous year’s
(D) farming mechanization in the village of Long Bow doubled the corn yield as it cut in half the previous year’s costs
(E) farming mechanization in the village of Long Bow doubled the corn yield while costs were cut to half that of the previous year


Please could you help me understand this SC

A- is wrong because its talking about cutting previous years costs
C- the use of "as" instead of "while" is incorrect.
D- the use of "as" instead of "while" is incorrect
E- "that" is incorrect. It should be "those"

left with B. But I find B too wordy. Moreover I wanted to understand the usage of cost and the following verb.

Costs (singular) will use the (Singular) verb was? While Cost (plural) will take the plural verb (were)

Somewhere in the forum I saw the opposite explanation given.

eg- The car costs be $10,000. Here car is singular subject and costs is singular verb
eg- The hotel rooms cost be $2000 per night plural subject- rooms. Plural verb- cost

Please correct me in my understanding

100. Although the phenomenon of withdrawal has always been the crucial physiological Leng for distinguishing addictive from nonaddictive drugs, it has become increasingly evident that not all regular heroin users experience withdrawal symptoms.
(A) addictive from
(B) addictive and
(C) addictive or
(D) between addictive or
(E) among addictive or

Please could you help me understand the usage of distinguish and distinction. I always use this as "Distinguish/distinction between X and Y" However none of the options above pose this structure

D- incorrect usage of between X or Y
E- incorrect usage of among
C- incorrect usage of or

I am now left with A and B. I want to select B but the word "between" is missing

Before we get into the weeds with grammar terminology, let's take an intuitive, non-technical look at the words in bold:

Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance, acting as sentinels and sounding a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.

All four of these words are doing the same thing, right? Each is a duty that can be taken on by the residents of the bat caves. So as a starting point, it makes sense that they could all be in the same grammatical form, since the residents do all four of those things (defending the entrance, acting as sentinels, sounding a warning, and scouting for food). So even if you don't think about the technicalities of grammar and parallelism at all, you might decide that this seems acceptably parallel, and move on.

If you do want some jargon: all of those four words (defending, acting, sounding, scouting) are gerunds, which is a fancy way of saying that they're "-ing" words that function as nouns. (More on "-ing" words in this article.)

And it wouldn't make sense for "sentinels" and "sounding" to be parallel to each other: "...acting as sentinels and sounding a warning..." If the two words in bold were parallel, then the sentence would be saying that the residents "act as sentinels" (which makes sense) and "act as sounding a warning" (which makes no sense). (More on parallelism in this video if anybody wants a basic refresher.)

Finally, you might be wondering why the word "and" appears so many times in the correct answer. I don't have a very satisfying answer to that, to be honest. In a sense, "acting as sentinels" and "sounding a warning" are all part of the same duty: "sounding a warning" is part of what the residents must do if they're "acting as sentinels." So those two activities are separated by their own "and", but they're still part of the larger structure of parallelism in the sentence ("defending..., acting and sounding..., scouting...").

I hope this helps!

Just to be clear: the meaning of "they" has nothing to do with parallelism here. "They" is just a pronoun, and it needs to refer back logically to a plural noun of some sort.

I suppose we could argue that there's some potential for ambiguity here, since "they" could refer back to "mammals" or "islands" or "West Indies." But I fundamentally agree with you: it really isn't remotely confusing, and it's obvious enough that "they" refers logically to mammals. (And for anybody who's wondering: pronoun ambiguity can be a problem, but it isn't an absolute rule on the GMAT. More on that in this video.)

So why is (C) wrong? Hang on, let me answer your question about (E) first, and then we'll compare the two.


"Ellipsis" is just a jargon-y way of saying that a few words have been omitted from a sentence because they're strongly implied, and really don't need to be included. Honestly, there are no absolute rules that dictate when it's OK to omit words, and when it isn't. The not-very-satisfying truth: if omitting a few words causes confusion, that's a problem. If omitting a few words doesn't make the sentence unclear or confusing, there's no problem. Of course, there's no rule that says when a sentence becomes "unclear" or "confusing" -- those things are, unfortunately, at least a little bit subjective.

But yes, it's fine to have ellipsis before the omitted words have actually been stated. In a sense, this is no different than when a pair of adjectives precedes a noun: in the phrase "green and red M&M's", for example, you wouldn't be tempted to write "green M&M's and red M&M's", right? It's abundantly clear that "green" describes the "M&M's", even though that (tasty) word doesn't appear until later in the sentence.

(And no, this post was not sponsored by any candy companies. But if you happen to run a food company, I can get you some killer product placement in GMAT lessons, in exchange for something tasty...)

OK, on to the real question: why (E) and not (C)?

For starters, "for determining" is the correct idiom here, not "to determine." And that's wildly unsatisfying, as are most of the 25,000 or so idioms in English. So that's admittedly not something that's likely to help you on the next question.

But notice the waste of words in (C). (E) is perfectly clear and parallel, right? Scientists are collecting clues for determining two things: how and when mammals colonized the West Indies. There's nothing WRONG with (C), exactly, but it's much nicer to have the two parallel elements -- "how" and "when" -- right next to each other, in a more succinct statement.

I hope this helps!

Hey Charles,

What're your thoughts on the difference between the two idioms "So ... that" and "So ... as to"

I saw this come up in a question here: https://gmatclub.com/forum/technically- ... 68593.html
In that question, I am confused as to why (A) is wrong.

For starters, this question looks deeply, deeply flawed. WTF is a "physiological Leng"?!? Please pay no attention to this question, because it either has an epic typo, or comes from a crappy, non-official source.

And in general, I don't recommend worrying TOO much about idioms, just because there are 25,000 of them in English, and you can't possibly memorize all of them during the course of your GMAT studies. But for whatever it's worth, here's the difference in meaning between various phrases that include "distinguish" or "distinction":

1. distinguish A from B: this basically means "to tell two things apart." For example, "Rob's two yappy dogs looked so similar that nobody could distinguish one dog from the other."
2. draw a distinction between A and B: this means that you're pointing out differences between A and B. For example, "Congressional candidate Leslie Cockburn drew a distinction between her opponent, Denver Riggleman, and herself by accusing him of promoting Bigfoot porn." (I am not making this up.)
3. distinguish A and B: this could mean a few different things. Depending on the context, "distinguish" could mean "to discern" or "to see": "It was so dark that Charlie could barely distinguish the homes and cars he passed." It could also mean "to become worthy of respect": "Steinhoff and Kattman distinguished themselves via outstanding service in the military."

But again: you don't want to overthink or over-study idioms.

I hope this helps!

113. Analysts blamed May’s sluggish retail sales on unexciting merchandise as well as the weather, colder and wetter than was usual in some regions, which slowed sales of barbecue grills and lawn furniture.
(A) colder and wetter than was usual in some regions, which slowed
(B) which was colder and wetter than usual in some regions, slowing
(C) since it was colder and wetter than usually in some regions, which slowed
(D) being colder and wetter than usually in some regions, slowing
(E) having been colder and wetter than was usual in some regions and slowed


I chose choice B. However it took me too much time to select B cause I was confused with the usage of ,slowing

COMMA + VERB-ing is used to show some result of an action or describe the action. Please could you highlight the action which it is modifying? Also please could you highlight the doer of the modified action and that of the modifier (slowing). Since in a verb-ing modifier the doer of both the action (the modified and the modifier action is the same) I was unable to find the doer of the two

Please could you help me understand the following SC

133. As part of their therapy, young polio victims learning to live with their disabilities were helped to practice falling during the 1950s, so that they could learn to fall without being hurt.
(A) As part of their therapy, young polio victims learning to live with their disabilities were helped to practice falling during the 1950s
(B) As part of their therapy, young polio victims learning to live during the 1950s with their disabilities were helped to practice falling
(C) Young polio victims learning to live during the 1950s with their disabilities were helped to practice falling as part of their therapy
(D) Young polio victims learning to live with their disabilities were helped to practice falling during the 1950s as part of their therapy
(E) During the 1950s, as part of their therapy, young polio victims learning to live with their disabilities were helped to practice falling

134. As rare as something becomes, be it a baseball card or a musical recording or a postage stamp, the more avidly it is sought by collectors.
(A) As rare as something becomes, be it
(B) As rare as something becomes, whether it is
(C) As something becomes rarer and rarer, like
(D) The rarer something becomes, like
(E) The rarer something becomes, whether it is

Could you explain why A is wrong?

I eliminated C&D because of the incorrect usage of like
I eliminated B&E because of the incorrect usage of whether. Whether.. or is used to show a parallel list between 2 entities. However out here the list is of 3.

Please could you correct me in my thought process

hi gmatninja and mikemcgarry
i am having issues understanding the usage of
1. being
2. having

what is the correct usage?

Hi, can a sentence beginning with " WITH" in GMAT SC be correct?
What is the usage of WITH in GMAT sentence correction?

Hey, you might find below article useful for understanding usage of being.It is written by master Ninja himself!
https://gmatclub.com/forum/experts-topi ... 42299.html

Technically, I suppose that the phrase beginning with “which” could, in theory, “reach behind” the other modifier (“that caused plant and animal distinctions”), but… why the heck would we want to write the sentence that way? It’s confusing and messy. In general, you want the modifier to be as close as possible to the thing it modifies, and in this sense, (D) isn’t ideal.

Put another way, if you think that the phrase “which marks the end of the geologic era” also modifies “an event”, then we would have two different modifiers for “an event”:

1. “that caused plant and animal extinctions”
2. “which marks the end of the geologic era…”

So if we’re saying that both of these modify an “event”, then they need to be parallel to each other. So something like “an event that caused plant and animal distinctions and that marks the end of the geologic era…” would be much, much clearer.

(E) avoids those problems entirely. The first modifier (“that caused the plant and animal extinctions”) is right next to the thing it modifies (“an event). So is the second modifier (“that mark the end of the geologic era” modifies “the plant and animal extinctions”). So the modifiers are much, much clearer than in (D).

I hope this helps!

Sorry that it took me so long to respond to you, brother Skywalker18! Your questions are good and dense, and they hurt my brain – in a good way! – and please forgive me for letting them get lost in the shuffle.


Be careful not to overthink this! “Ellipsis” is just a fancy way of saying “sometimes we omit words because the sentence is perfectly clear without them.”

And I would love for there to be firm grammatical rules for ellipsis, but that’s just not how it works, sadly. It’s entirely context-dependent.

Whenever you run into these situations on the GMAT, you want to ask yourself: if one answer choice omits a few words and another answer choice doesn’t, do the omitted words add anything to the meaning or clarity of the sentence?

In your example, “Siri is smarter than Alexa and Cortana (are)”, I don’t think it makes a big difference if you omit the word “are.” The sentence is perfectly clear without it, right?

And more importantly: it's rare that the GMAT gets terribly nitpicky about ellipsis. Your example is very much in a grey area where it doesn’t matter much if you omit or include the “are.” On official questions, if the presence or absence of a word is a deciding factor, then it will DEFINITELY affect the meaning or grammar or clarity in some way -- and if you're really paying attention to the meaning, the difference between the right and wrong answers will be 100% clear.


I’m not sure about this one, to be honest. I think the 2nd one is marginally clearer, but do we really think that the first sentence is a problem? If I had to choose between these, I’d go with #2, but the GMAT is unlikely to give you a case like this, in which either sentence is defensible, and the difference in clarity is very, very minor… and there are no other issues that distinguish the two sentences.


Awesome example! Yes, this is the heart of things. If the omission causes a meaning problem, that’s a serious crime.

Anybody reading this who isn’t @skywalker18: if you only read one part of this post, read this part above!


That’s a remarkably difficult question, and all of us here at GMAT Ninja have struggled to say or write anything intelligent about it. This post is pretty much the best we’ve come up with, and I’m worried that it still isn’t very good. Check it out, and let me know if it doesn’t do the trick?

I hope this helps!

(C) is better than (E), as it turns out. Here it is again, with everything besides (C) and (E) removed:

This is a pretty unsatisfying question, unfortunately.

First, let’s talk about the non-issues. We could argue about the idiom (“went to pay” vs. “used for paying”), but I’m not convinced that one is better than the other. I think that “while” does a nicer job of indicating that these actions were simultaneous, but I'm not sure that “as” is WRONG here, exactly.

The bigger issue is where vs. with: “where much of its profit went to pay higher taxes” very clearly and succinctly modifies “overseas.” But it’s hard to make sense of “with” here. Check out this post for more on “with”, but the short version is that in a construction that uses “clause + with”, “with” generally modifies the preceding verb. For example, in the phrase "I ate dosas with a smart guy named Daagh", the part in red gives us more information about what I did while I ate dosas. Fair enough.

And that just doesn’t seem to work in the sentence you asked about: “it was profitable overseas, with much of the profit used for paying higher taxes” – huh? How does "with much of the profit used for paying higher taxes" modify "was", or even the fact that the company was profitable overseas? It doesn't make a whole lot of sense.

We could also argue that in (C) “much of its profit went to pay higher taxes”, is a nice, clear, active clause, since the word “went” operates as a verb. However, the phrase “with much of the profit used for paying higher taxes” is more passive – “used” is basically functioning as a modifier, not a verb. Is that a terrible crime? No! This isn’t a major issue, but I’d prefer the active and clearer option, since it’s available to us in (C).

But the “where” vs. “with” thing is a pretty big deal, even if it isn’t the easiest thing to explain.

I hope this helps!

Answered in detail here: https://gmatclub.com/forum/thai-village ... l#p2191138. Enjoy!

Hi GMATNinja

Sir please help me on the below solution. I am not able to understand why would is used and not will.

https://gmatclub.com/forum/gen-joseph-h ... 70243.html