The industrial pollutants known as PCB's were first manufactured in

Question

The industrial pollutants known as PCB's were first manufactured in 1929 and were used as coolants for electrical equipment in Europe and North America until the 1970's, when studies showed  that the compounds had entered the food chain and were harmful to some animals .

(A) that the compounds had entered the food chain and were harmful to some animals

(B) the compounds to have entered the food chain and be harmful to some animals

(C) the entry of the compounds into the food chain as harmful to some animals
 
(D) the entry of the compounds into the food chain and its harmfulness to animals

(E) the compounds entering into the food and harming some animals

mikemcgarry · Accepted Answer

Dear mun23 , Idiomatically, the verb " show " (like the verbs " think ", " tell ", " know ", " believe " and a host of other "cognitive" verbs) must take a "that"-clause. show that P does Q The word "that" is omitted in colloquial, informal English, but it's absolutely needed on the GMAT. The only choice that does this correctly is (A) . We can't use the infinitive structure show P to do Q This is the mistake of (B) . The other choices have a variety of idiomatically incorrect options --- participles, "P as Q", etc. The verb "show" demands a "that"-clause. Does this make sense? Mike :-)

aditya8062 · Answer

just to add the option C ,D and E is implying that the study literally showed the compounds entering into the food chain as if it is some kind of physical process !!

TooLong150 · Answer

How are "show" and "tell"

cognitive verbs?

mikemcgarry · Answer

Dear TooLong150 As I am using the term, a "cognitive" verb does not necessarily imply incredible intelligence. It simply means that the direct object of the verb is a " that "-clause containing some factual information. Think about the factual piece of data: Henry VIII was King of England for 37 years . I can know that Henry VIII was King of England for 37 years. I can show the class that Henry VIII was King of England for 37 years. I can tell you that Henry VIII was King of England for 37 years. Because all these verbs can take factual data as their direct object, I classify them all as cognitive. Does all this make sense? Mike :-)

honchos · Answer

Is there a way to classify and identify cognitive verb.

mikemcgarry · Answer

Dear honchos , I'm happy to respond. :-)

I would say, that's not the best question to ask. I would say that it's better just to study the GMAT idioms, and learn the idioms that go with each individual verb. Here's a set of GMAT idiom flashcards: https://gmat.magoosh.com/flashcards/idioms I hope this helps. Mike :-)

liu1993918 · Answer

Can someone explain the verb tense in A, please? 
I thought the compounds would continue enter the food chain after the studies show the results. 
This sentence doesn't have some markers to indicate we should use past perfect verb tense.

EducationAisle · Answer

Two things happened in the past:

i) In the 1970's, studied showed something
ii) Compounds entered the food chain (at some unspecified time between 1929 and 1970`s)

When  two  events happen in the past, and we need to depict the  chronological sequence  of the two events, we use  past perfect  to depict the event that happened  earlier , in this case:  Compounds entered the food chain .

This is in fact the most  classical  usage of past perfect.

p.s. Our book    EducationAisle Sentence Correction Nirvana    discusses  past perfect  tense, its application and examples in significant detail. If someone is interested, PM me your email-id, I can mail you the corresponding section.

mikemcgarry · Answer

Dear liu1993918 , I'm happy to respond. :-)

With all due respect to EducationAisle , I would frame this a bit differently. This is indirect speech. The verb " showed " is a communication verb (like " say ", " tell ", " express ", etc.) We are not given a direct quote from the studies: instead, we are simply told what they showed. This is indirect speech . In indirect speech, the verb tenses follow a set of rules know as sequence of tenses. See this article: https://magoosh.com/gmat/2013/sequence-o ... orrection/ If the speaker (in this case, the " studies ") is speaking or communicating in our past, and it speaks about something in the speaker's past, we communicate that with the past perfect tense. Does all this make sense? Mike :-)

kumarashok29 · Answer

IMO - A

The industrial pollutants known as PCBs were first manufactured in 1929 and were used as coolants for electrical equipment in Europe and North America until the 1970`s,when studies showed  that the compounds had entered the food chain and were harmful to some animals .
>> correct idiom :  show that X is Y . Only option A has this correct idiomatic structure. Lets analyse the options further.
(A)  that  the compounds  had entered the food chain  and  were harmful to some animals .
>> correct idiom. Corrent tense transition (use of double past. entering happened first and then became harmful)
(B) the compounds  to have  entered the food chain and be harmful to some animals
>> to have entered the food chain...awkward
(C)  the entry of  the compounds into the food chain as harmful to some animals
>> studies showed the entry of the comp....again awkward
(D)  the entry of  the compounds into the food chain and its harmfulness to animals
>> same as C
(E) the compounds  entering into the food and harming  some animals
>> meaning as if comp. was entering just to harm some animal. Is this motto of the compound? nonsensical.

tronghieu1987 · Answer

Hi Mik,

Please help me to clarify choice A. Although I understand its meaning, I did not choose it because, for the purpose of parallelism and unambiguity, I thought there must be a second "that" before "were harmful...", as ".... and that they were harmful...". Without it, I think this sentence is ambiguous since "were harmful..." could refer to "studies".

About choice D, I don't think the absence of "that" after "showed" is a problem. "entry" and "harmfulness" are nouns, not facts. So "the studies showed the entry and the harmfulness" is ok, just as "The deep analysis of GMAT score shows his weakness in SC part". Also, the pronoun "it" refers to "entry", and I don't think pronoun ambiguity is a reason to eliminate a choice in GMAT SC.

I agree that the meaning in choice A is better, but I still think D is ok. So please help me with this. Thank you so much!

mikemcgarry · Answer

Dear tronghieu1987 , I'm happy to respond. :-)

The parallelism in choice (A) is between two verbs for the same subject. There is absolutely no ambiguity about this. (A) that the compounds had entered the food chain and were harmful to some animals . In other words: ...that the compounds //had entered the food chain and //were harmful to some animals. In this construction, it's very clear that the two verbs are parallel. We do NOT need to insert " that they " to change this from parallel verbs to parallel clauses, because that would be wordier and awkward. The basic structure of (D) is grammatically correct. You are right: when the verb " to show " is followed by a simple noun direct object, not a clause, there is absolutely no need of the word " that ." Here are the problems with (D). 1) It's not so much a mistake in the pronoun; rather, the pronoun changes the meaning. Exactly what causes harm to the animals? According to the prompt, it would be the compounds themselves. According to (D), it's the entry of the compounds, not the compounds, that causes harm. Hmmm. That's subtle, but it is a change in meaning, which is not allowed. 2) Even if there were no pronoun problem, think about it. Choice (A) had full clauses with full verbs: it was packed with active language. Choice (D) is stuff full of nouns. This may be grammatically correct, but it's a rhetorical disaster. See: https://magoosh.com/gmat/2013/active-verbs-on-the-gmat/ The phrasing in (A) is direct, powerful, and rippling with action. The phrasing in (D) clumsy and congealed into inaction. Think about the scientist who would speak this sentence. He is telling us about how dangerous these chemicals are. He would want to be persuasive about this important point. Active & direct language, containing full verbs inside full clauses, is very persuasive. Indirect awkward language that freezes all the action inside nouns is not very exciting at all. That's really the problem with (D). So what if it is grammatically correct---it's a rhetorical trainwreck! Remember, the GMAT SC is not simply about grammar. It's about how a sentence works at the levels of grammar, logic, and rhetoric. All three are important, and if you focus on one and ignore the other two, the GMAT will frustrate you. Does all this make sense? Mike :-)

EducationAisle · Answer

Hi Mike, even  without  the usage of  showed ,  past perfect  is the right tense here.

So, for example, following sentence (which removes  showed  and hence, has been slightly altered).

The industrial pollutants known as PCB's were first manufactured in 1929 and were used as coolants for electrical equipment in Europe and North America, but by 1970's, the compounds had entered the food chain and were harmful to some animals .

EducationAisle · Answer

Hi tronghieu1987, I had discussed this issue about repetition of that in detail in this post: gmatprep-challengeq-the-bones-of-majungatholus-atopus-176167.html#p1394601

mikemcgarry · Answer

Dear  EducationAisle ,
My friend, the example sentence you provided would never appear as such on the GMAT. You have used the simple past, " manufactured " and " used ," for the earlier events, and then the past perfect for a considerably later event. The GMAT would scrupulous avoid this confusing scenario. It's true that if the latter half stood as a sentence on its own, then the past perfect would be justified. It's harder to appreciate the GMAT's perspective on the sentence as a whole. 
Mike

EducationAisle · Answer

Hi Mike, thanks for your post.

So, are you suggesting that the usage of Past Perfect on GMAT would always be accompanied by  indirect speech ?

Also, curious to know why you say it's a  confusing scenario .

mikemcgarry · Answer

Dear EducationAisle , I'm happy to respond. :-)

First of all, I wouldn't say that, on the GMAT, indirect speech always requires the Past Perfect Tense. The GMAT is quite nuanced on this point. If another feature of the sentence (" several years earlier ," etc.) makes clear the time reference, then the GMAT may choose to forgo entirely the Past Perfect. It really depends on the subtleties of a case-by-case basis. When the GMAT does use the Past Perfect in a non-indirect-speech scenario, it always follows the rule that the event furthest in the past, before the other past events, is in the past perfect. It's simply a by-product of the GMAT's conventions that the action in the past perfect is the earliest action in the entire sentence, the action furthest in the past. In that light, think about the sentence you proposed: The industrial pollutants known as PCB's were first manufactured in 1929 and were used as coolants for electrical equipment in Europe and North America, but by 1970's, the compounds had entered the food chain and were harmful to some animals . Now, think about the time-relationship of the verbs in that sentence. The most recent action, Action #1, was " were harmful ," and the Action #2 " had entered " happened before this more recent action and appears in the past perfect. So far, so good. But then, we have two actions even further in the past: Action #3 " were first manufactured " and Action #4 " were used ." Actions #3 & #4 happened before Action #2, but Action #2 is in the past perfect, and Actions #3 & #4 are not! We have one action in the past perfect, and two actions that happened before the event in the past perfect that are in the simple past tense. If we put these actions in historical sequence, we would get: Deepest past --- Action #3 --- Action #4 --- Action #2 ---Action #1---Present Time According to the GMAT convention, if we are going to use the past perfect for any verbs at all, then the action in the furthest past should be one of the verbs that has the past perfect. Admittedly, sometimes the GMAT relies on other indicators, such as the year dates in this sentence, to indicate sequence, but then the GMAT entirely forgoes the past perfect tense, and relies exclusively on these other indicators. What's confusing is using the past perfect for an event that is relatively more recent and not using it for the even furthest in the past. Even if this sentence is technically grammatically correct, it would not appear on the GMAT because the conventions are mixed and it would be thereby confusing to students. Does all this make sense? Mike :-)

EducationAisle · Answer

Hi Mike, thanks for your elaborate post.

My question was  slightly  different. I did not intend to ask whether indirect speech   always   requires the Past Perfect Tense. My question was the  other  way round: Does the the Past Perfect Tense  always  require an indirect speech. My answer is  no  and hence the reason I re-articulated this sentence  removing  the indirect speech  showed that , while still  retaining  the  past perfect .

That’s  exactly  what’s happening here.

We have a  specific  year (1929), which clearly  has  to be in  simple past . Note that this  cannot  be in Past Perfect, because Past Perfect (in fact,  all  perfect tenses for that matter) are associated with  unspecified  time. So, there is no confusion on the sequence of events, in the sentence that I have proposed:

i) PCB's were first manufactured in 1929 – Clearly this is the  oldest  event (the usage of  first  in this context makes it very clear)

ii) PCB's were used as coolants for electrical equipment in Europe and North America - clearly this could  not  have happened before PCB’s were manufactured

iii) by 1970's, the compounds had entered the food chain – Usage of  past perfect  is apt here, because it clearly indicates that this act of  entering the food chain  occurred sometime in or before 1970's, but the time frame (of entering the food chain) goes back  only  till 1929.

iv) by 1970's, the compounds were harmful to some animals – I think we have a common understanding on this one that the usage of  Simple past  is  appropriate  here.

Grammatically , this latter half ( by 1970's, the compounds had entered….. ) actually  is  an Independent clause (as you would obviously know that  coordinating conjunctions  and  semicolons  connect two Independent clauses; here,  but , a coordinating conjunction is used).

However, if you are suggesting that the rest of the sentence should not have appeared at all, then the  sentence  would have been:

By 1970's, the compounds had entered the food chain and were harmful to some animals .

The above sentence would mean that from  eternity  in the past, till 1970’s, the compounds had entered the food chain. However, clearly the intent of the sentence is to not go back from 1970’s to  eternity , but to go back  only  till  1929 . The  first  part of the sentence (by categorically mentioning  1929 ) serves as a  reference  to clearly indicate that the time frame of reference is  not  from  eternity to 1970’s ", but from  1929 to 1970’s .

karant · Answer

Hello Mike,

Could you please explain the usage of past perfect in this sentence in the light of another OG question.  His studies of ice-polished rocks in his Alpine home land, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose the concept of an age in which great ice sheets had existed in now currently temperate areas.

In both the questions, some studies led to some results. However,  in industrial pollutant  question usage of past perfect is justified whereas in ice sheet question usage of past perfect is considered wrong. Why ? Please explain.

Thanks !

The industrial pollutants known as PCB's were first manufactured in

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The industrial pollutants known as PCB's were first manufactured in

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