Since 1990 the global economy has grown more than it did

[RonPurewal]

Hi, so if the question states "the growth of global economy during 1990 & 2000 was more than that during 10,000 yrs,...", this sentence is correct then?

Thank you,

* "During 1990 and 2000" doesn't make any sense, unless you are talking about only those two years (and not the 9 years that come between them). Not very reasonable.

* "The growth was more" isn't idiomatic. In fact, you really can't write anything like this -- "the speed was more", "the height was more", etc., all wrong.
You'd need "grew more". Or "grew faster", or "the growth was faster".

* If you are talking about choice (B) -- which I assume you are -- then the part that you cut off is also wrong, because "when agriculture began" and "1950" are not parallel.

Please quote the answer choices you're talking about. Thanks.

[reotokate]

Gottya! Thanks much!

[RonPurewal]

Sure.

[chwera58]

How about B?
Some people said that "from when" is not right.
Can "that" in choice B represents "the growth of the global economy"? Or "that" could only refer to one noun?
Thanks in advance.

you can't use 'that' in this sort of construction, because constructions using 'that of' (or other preposition after 'that') must have EXACTLY parallel structures. in other words, if the second half says 'that during 10,000 years', then the preceding half must say 'the growth of ___ during something else' (or some other time preposition, such as before or after, in place of during).

there's nothing ungrammatical about 'from when', because the clause starting with 'when' is a perfectly legitimate noun clause (i.e., 'when agriculture began' serves as a noun. however:
- it's possible that the gmat does consider such constructions wrong; the only way to tell is to see if they say so in any official answer choices
- regardless of where the gmat stands on the issue, 'the beginning of agriculture' is unquestionably better than 'when agriculture began' (i.e., an actual noun is almost always superior to a circuitous noun clause, when possible)

Hi, Ron, I ruled out choice B bacause the meaning of the sentence does not make sense. What's being compared here is the growthes of two periods, i.e. 1) 1990-the time of this report & 2) 10,000 yrs; however, the use of "has been" in Choice B, at least to me, seems to say that the growth itself at every moment during period 1) is greater than 2) period. The meaning is thus distorted.

Please kindly correct me if I am wrong. Thank you.

[danli311]

Isn't 'it' in choice D, E ambiguous?
'it' could refer to either 'growth' or 'global economy'? Thanks.

Yes, correct. That is *another* reason to eliminate D, E (in addition to those discussed above). Nicely done.

Dear instructors,

I would like to clear my thoughts on the pronoun issues in answer choice - A, D and E, please correct me if my understanding is wrong.

In both D and E - "it" refers to the whole The growth of the global economy between 1990 and 2000 part because between 1990 and 2000 is an essential modifier modifying the growth of the economy. But since the growth of the global economy since 1990 cannot "has been for 10,000yrs"(as in D) nor can it "did for the 10,000yrs" (as in E), both D and E are wrong.

However, in the correct answer A, the essential modier between 1990 and 2000 actually modifies grew, and it refers to the global economy alone, hence, no ambiguity.

Is my reasoning correct? I am not sure with my understanding on the essential modifier and referent part. Thank you in advance!

[RonPurewal]

Hi, Ron, I ruled out choice B bacause the meaning of the sentence does not make sense. What's being compared here is the growthes of two periods, i.e. 1) 1990-the time of this report & 2) 10,000 yrs; however, the use of "has been" in Choice B, at least to me, seems to say that the growth itself at every moment during period 1) is greater than 2) period. The meaning is thus distorted.

Please kindly correct me if I am wrong. Thank you.

That's pretty much the right idea. In fact, you can't use "has been" at all in a sentence like this, because you're describing two absolute statistics (not ongoing processes).
I.e., "the amount by which the global economy grew between year x and year y" is just a single number. It's not an ongoing process, and it's not something that can change, so "has been" isn't logical.

[RonPurewal]

Isn't 'it' in choice D, E ambiguous?
'it' could refer to either 'growth' or 'global economy'? Thanks.

Yes, correct. That is *another* reason to eliminate D, E (in addition to those discussed above). Nicely done.

Dear instructors,

I would like to clear my thoughts on the pronoun issues in answer choice - A, D and E, please correct me if my understanding is wrong.

In both D and E - "it" refers to the whole The growth of the global economy between 1990 and 2000 part because between 1990 and 2000 is an essential modifier modifying the growth of the economy. But since the growth of the global economy since 1990 cannot "has been for 10,000yrs"(as in D) nor can it "did for the 10,000yrs" (as in E), both D and E are wrong.

However, in the correct answer A, the essential modier between 1990 and 2000 actually modifies grew, and it refers to the global economy alone, hence, no ambiguity.

Is my reasoning correct? I am not sure with my understanding on the essential modifier and referent part. Thank you in advance!

Perfect understanding.

[josefdong]

Dear instructors,

I would like to clear my thoughts on the pronoun issues in answer choice - A, D and E, please correct me if my understanding is wrong.

In both D and E - "it" refers to the whole The growth of the global economy between 1990 and 2000 part because between 1990 and 2000 is an essential modifier modifying the growth of the economy. But since the growth of the global economy since 1990 cannot "has been for 10,000yrs"(as in D) nor can it "did for the 10,000yrs" (as in E), both D and E are wrong.

However, in the correct answer A, the essential modier between 1990 and 2000 actually modifies grew, and it refers to the global economy alone, hence, no ambiguity.

Is my reasoning correct? I am not sure with my understanding on the essential modifier and referent part. Thank you in advance!

Perfect understanding.

Hi Ron, I want to clarify the usage of "the" , which seems not to be discussed before.

I think "from the beginning of agriculture to 1950" is an essential modifier of 10000 years, so in order to specify this time interval(it is not other time span of 10000 years), we should put "the" in front of 10000 years.

In terms of this, I can eliminate B,C,D. But is this problem a "make-or-break" one? Thank you very much.

[RonPurewal]

Hi Ron, I want to clarify the usage of "the" , which seems not to be discussed before.

I think "from the beginning of agriculture to 1950" is an essential modifier of 10000 years, so in order to specify this time interval(it is not other time span of 10000 years), we should put "the" in front of 10000 years.

In terms of this, I can eliminate B,C,D. But is this problem a "make-or-break" one? Thank you very much.

The most important piece of advice I can offer here is that no gmat problem will ever depend on the usage of "a"/"an"/"the".
If such a problem were to appear on the exam, then it would discriminate heavily in favor of speakers of English and/or Western European languages, and heavily against most speakers of Eastern European and Asian languages (which tend not to have any equivalent of "a"/"an"/"the").

----- YOU DON'T NEED TO KNOW ANYTHING BELOW THIS LINE FOR THE GMAT -----

If the description of the 10,000 years does not follow a comma, then your elimination here works.

On the other hand, if the description of the time period does follow a comma, then it's the opposite -- you don't want "the". (Remember -- modifiers behind commas should, in general, be removable without affecting the meaning of the sentence.)

E.g., both of the following are correct:
James ran six marathons in the 60 days between the beginning of March and the end of April.
James ran six marathons in 60 days, from March 1 to April 29.
Note why "the" doesn't work in the second sentence -- if you take the modifier away, then "in the 60 days" makes no sense at all.

[eggpain24]

HI,Ron

I just cannot ensure whether my understanding of the simple past "did" in choice A is correct, please help me confirm this, thank you !

from the beginning of agriculture to 1950 → it is a past timeframe, namely an isolated period in the past, so the usage of "did" is appropriate

if "past perfect" were to be used here, namely "had been" , we should had a "simple past" action, which also has a direct bearing with " past perfect"

[ZoeH439]

How about B?
Some people said that "from when" is not right.
Can "that" in choice B represents "the growth of the global economy"? Or "that" could only refer to one noun?
Thanks in advance.

you can't use 'that' in this sort of construction, because constructions using 'that of' (or other preposition after 'that') must have EXACTLY parallel structures. in other words, if the second half says 'that during 10,000 years', then the preceding half must say 'the growth of ___ during something else' (or some other time preposition, such as before or after, in place of during).

there's nothing ungrammatical about 'from when', because the clause starting with 'when' is a perfectly legitimate noun clause (i.e., 'when agriculture began' serves as a noun. however:
- it's possible that the gmat does consider such constructions wrong; the only way to tell is to see if they say so in any official answer choices
- regardless of where the gmat stands on the issue, 'the beginning of agriculture' is unquestionably better than 'when agriculture began' (i.e., an actual noun is almost always superior to a circuitous noun clause, when possible)

hi Ron

there are my understandings of this question

1.because the author wants to compare the global economy with itself in different periods，it is very clear that the author prefer the structure emphasizing the action ,so A is much more preferable . In B,the use of "that" seem to tell us that the comparison is between different things(since that/those are used as "new copys" to refer the former noun ), in fact, however, in any period ,the"growth of the global economy" is "the growth of the economy" itself,so the use of "that "makes no sense here .Moreover, the structure in B makes no sense neither.
2. “growth” is an action noun,so it is much conciser and more effective to use its verb form "grow" to reflect the "grow" trend.

[cherryj222]

How about B?
Some people said that "from when" is not right.
Can "that" in choice B represents "the growth of the global economy"? Or "that" could only refer to one noun?
Thanks in advance.

you can't use 'that' in this sort of construction, because constructions using 'that of' (or other preposition after 'that') must have EXACTLY parallel structures. in other words, if the second half says 'that during 10,000 years', then the preceding half must say 'the growth of ___ during something else' (or some other time preposition, such as before or after, in place of during).

there's nothing ungrammatical about 'from when', because the clause starting with 'when' is a perfectly legitimate noun clause (i.e., 'when agriculture began' serves as a noun. however:
- it's possible that the gmat does consider such constructions wrong; the only way to tell is to see if they say so in any official answer choices
- regardless of where the gmat stands on the issue, 'the beginning of agriculture' is unquestionably better than 'when agriculture began' (i.e., an actual noun is almost always superior to a circuitous noun clause, when possible)

Ron, I have a question here regarding your explaination of "that" in choice b. In following example, it seems that "thoes＋prepositon" does not need to have exactly parallel structure before it.
This is a prep problem:
Today's techonology allows manufacturers to make small cars that are more fuel efficient than thoes at any othet time in production history.

[RonPurewal]

How about B?
Some people said that "from when" is not right.
Can "that" in choice B represents "the growth of the global economy"? Or "that" could only refer to one noun?
Thanks in advance.

you can't use 'that' in this sort of construction, because constructions using 'that of' (or other preposition after 'that') must have EXACTLY parallel structures. in other words, if the second half says 'that during 10,000 years', then the preceding half must say 'the growth of ___ during something else' (or some other time preposition, such as before or after, in place of during).

there's nothing ungrammatical about 'from when', because the clause starting with 'when' is a perfectly legitimate noun clause (i.e., 'when agriculture began' serves as a noun. however:
- it's possible that the gmat does consider such constructions wrong; the only way to tell is to see if they say so in any official answer choices
- regardless of where the gmat stands on the issue, 'the beginning of agriculture' is unquestionably better than 'when agriculture began' (i.e., an actual noun is almost always superior to a circuitous noun clause, when possible)

hi Ron

there are my understandings of this question

1.because the author wants to compare the global economy with itself in different periods，it is very clear that the author prefer the structure emphasizing the action ,so A is much more preferable . In B,the use of "that" seem to tell us that the comparison is between different things(since that/those are used as "new copys" to refer the former noun ), in fact, however, in any period ,the"growth of the global economy" is "the growth of the economy" itself,so the use of "that "makes no sense here .Moreover, the structure in B makes no sense neither.
2. “growth” is an action noun,so it is much conciser and more effective to use its verb form "grow" to reflect the "grow" trend.

I'm not sure what you are trying to ask here.

[JaneC643]

Sorry to bump this thread again.

After reading all of posts, I have a question about the the use of " it" in the correct question A. Why is it not " that"? I also find a similar question in another gmat prep question.

If current trends continue, by the year 2010 carbon emissions in the United States will soar to a level more than one-third higher than were those in 1990, according to official projections.
A. will soar to a level more than one-third higher than were those
B. will soar to a level more than one-third higher than that
C. would soar to a level more than one-third higher than is was
D. would soar to a level more than one-third higher than those
E. would soar to a level more than one-third higher than they were

The correct answer of this problem is B, and here we use "that" to refer to "a level". So when we use "it" and when we use" that"?
Thank you!

[ShawnY790]

read here:
[]

note that this sentence fits the third form given in that post -- "did" is a form of "to do", and "has grown" is a tense of the action verb "grow" (it's called the "present perfect tense", if you like to name these things)

notice that the reverse of this kind of structure would not be permissible; if you had just "has" as the second part of the parallel structure, then that's no longer the present perfect tense of an action verb, and so in that case you would also need a corresponding form of "have" in the first part.

Hi Ron,

Sorry to delete the URL in your quote because I was somehow not allowed to add URL in my post.

I previously found the summary of ellipsis in comparison clauses led by as/than in a grammar book. After reading this whole thread, and particularly the one I quote, I feel there must be some problems with that summary. However, since the summary is comprehensive and concise in my opinion, I want to post it here so that it would be of great use after proper corrections.

The summary specifies four scenarios under which ellipsis should be applied.

1. When the main clause and the comparing clause share the same verb, we can use "do/did/does" to replace the verb in the comparing clause.

e.g. she ate more apples than I did.

2. When the main clause and the comparing clause share the same linking verb "be", we can either leave out or keep the "be" in the comparing clause.

e.g. He is taller than me.
He is taller than I am.

3. When the main clause and the comparing clause share the same subject and verb, we can leave out the subject and verb in the comparing clause.

e.g. He is taller than (he was) five years ago.

4. When the verb of the main clause is of the form: "auxiliary verb (have, has , will etc.) + verb" or "modal verb(can, could, may etc.) + verb", we usually only keep the auxiliary/modal verb.

e.g. John has always eaten more meat than Paul has. (I will just steal ayushrastogi82's example LOL)

Apparently, based on your reply, rule #4 is incorrect or at least incomplete.

My question is: is there a way to fix rule #4, or am I totally wrong in terms of the mindset to solve comparison questions.

I ask the mindset because I noticed that you judged the correctness of comparisons by looking at the comparing clause first, and then moving to the main clause to see whether the forms matched. Whereas for me, the usual order would be: main clause --> comparing clause.

Thank you a lot.

Shawn