Since 1990 the global economy has grown more than it did

[RonPurewal]

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

You won't often be able to reason in that direction, since you won't be able to tell how much of the first part is included in the comparison.

The second part, on the other hand, follows a comparison signal word ("than", "as", etc.), so it's bounded. You know exactly what the second part is. From that point, you can make an informed comparison to the first part.

[RonPurewal]

Finally, don't forget:
Comparison sentences are "beauty contests".
DO NOT judge INDIVIDUAL choices!

To judge individual comparison sentences, you'll need the skill set of a professional editor.
For a "beauty contest", on the other hand, all you have to do is look at the choices and ask yourself, "Which of these looks more/most like its counterpart?"

An excellent test case is this problem:
can-somebody-help-me-out-with-this-question-t4278.html
In the problem text, the weird quote marks are supposed to be dashes; the punctuation was somehow corrupted when the forum was switched to the new web layout. The same thing happened to lots of other dashes on the forum (though, weirdly enough, not to all of them).

If you view that problem as a "beauty contest", it's super easy. In choice B, the second part looks EXACTLY like the first part. In the other choices, there's virtually no resemblance at all. Black, white.

If that problem is SUPER EASY, you're thinking about comparisons in the right way. If it's hard, you're not.

[DiZ806]

I agree with A but wouldn't it be clearer if it was re-worded as Since 1990 the global economy has grown more than it did during the past 10000 years from the beginning of agriculture? Or is this already implied?

Since it says "during the 10,000 years from the beginning of agriculture to 1950" I think that implies that the beginning of agriculture happened approximately 10,000 years before 1950.

I am a little confused about A
IT refer to the economy,but I remerber that "IT" has the previous character.Such as
The weather in NewYork is more warmer than it in Chicago Wrong!!!!!!!Because "it " not refer to the weather but the weather in New York
So!!!
Why in this case it "refer to the economy itself,not with since 1990????????

[RonPurewal]

"the global economy" is not followed by any modifiers (as contrasted with "the weather in NY" in your example). so, it has no "character" to transmit to the other part of the sentence; it's just "the global economy (in general)".

[RonPurewal]

also...

The weather in NewYork is more warmer than it in Chicago Wrong!!!!!!!Because "it " not refer to the weather but the weather in New York
So!!!
Why in this case it "refer to the economy itself,not with since 1990????????

please use single pieces of punctuation.

what you're doing here (7 exclamation points? 8 question marks?) is the internet equivalent of banging on my door and shouting like a crazy person. please don't; this is a professional forum. thanks.

[DiZ806]

also...

The weather in NewYork is more warmer than it in Chicago Wrong!!!!!!!Because "it " not refer to the weather but the weather in New York
So!!!
Why in this case it "refer to the economy itself,not with since 1990????????

please use single pieces of punctuation.

what you're doing here (7 exclamation points? 8 question marks?) is the internet equivalent of banging on my door and shouting like a crazy person. please don't; this is a professional forum. thanks.

Thank you Ron.
Thanks for your remind.I really appreciate your help.
I hope you could forgive me for my exciting mood after talking with my friend about the knowledge poins for several bouts.
I will not do it.

[RonPurewal]

thanks!

[happyface101]

"had been" is not parallel to anything in the other half of the sentence; in order to use a parallel structure that contains a form of "to be", you must have another form of "to be" in the other half of the parallel structure."

Ron can you please elaborate on this briefly? Are you saying there should be another past tense verb in order for "had been" to be correctly used?

[RonPurewal]

past tense isn't necessary.

but, to justify the use of 'had been', one of 2 things should be present:

1/
another form of 'be' (might be past tense, might not),

2/
a construction that can follow 'had been' (probably '__ing' or '__ed' type construction).

this sentence has neither.

[SmitR723]

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 assume that the rule applies to "those+preposition" in a comparison sentence (such as an "as...as" sentence and a "than" sentence)

I have read through all OG 10 SC questions, and it seems like that 2 of them are exceptions:
19. In addition to having more protein than wheat does, rice has protein of higher quality than that in wheat, with more of the amino acids essential to the human diet.
112. Domestic automobile manufacturers have invested millions of dollars in research to develop cars even more gasoline-efficient than those at present on the road.
(I know that I am not supposed to post OG questions because of the copyright issue; hope that it is okay to post without posting the full questions; otherwise, please delete my questions and leave the question #s so that other can refer to their OG books)

I believe that the "exactly parallal structures" refer to a pair of prepositional phrases serving the similar function. If my understanding is correct, then #19 is an exception to your rule.
In #112 "cars" isn't followed by preposition....

Did I interpret your rule incorrectly?
Thanks in advance.

wow. whoever you are, we should hire you to do research for us.

in #112, "at present" isn't part of the parallel construction; it's an idiomatic expression with the same meaning as the word "now". i.e., you could write this as ...than those now on the road, and the meaning would stick. so that is a non-issue.

#19 is interesting. there's still LOGICAL parallelism - you have the protein contained in rice, and you have the protein contained in wheat - but the GRAMMATICAL parallelism isn't lock-step: you have "rice has protein" vs. "that in wheat". in other words, while both halves refer to the protein contained in a particular type of food, they do so in slightly different ways.
the lesson here is that we shouldn't complain, but, rather, we should learn: if the logical parallelism is absolutely clear, then the gmat will tolerate slight anomalies from the ideal of exact grammatical parallelism.

How about the following sentence. EXACT PARALLELISM is not followed here as well.
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 that in 1990, according to official projections.

[tim]

Can you clearly articulate why you don't think parallelism is adhered to in the sentence you wrote?

[thanghnvn]

we can not say
growth is more
we have to say
growth is greater

am i correct?

[RonPurewal]

you wouldn't say either of those. you'd say that something grew more.

[JustinCKN]

I've learned one rule on the basis of which I marked off A, but now I'm very confused.

Rule: when "have/has/had" is an aulixiary verb, you do have a choice to repeat or not repeat the past participle, but you cannot change "have/has/had" to "do/does/did"

For example:
John has always eaten more meat than Paul has eaten.(correct)
John has always eaten more meat than Paul has. (correct)
John has always eaten more meat than Paul does. (incorrect)

A says: Since 1990 the global economy has grown more than it did during the 10,000 years from the beginning of agriculture to 1950

If OA is A, then it is voilating this rule.

The only difference I can point out between the rule and the choice A is that the above mentioned rule has 2 different subjects while choice A has only one subject.

Could any instructor clarify on the same?

read here:
http://www.beatthegmat.com/soar-t62473-15.html#280069

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:
According to the discuss above, I can not figure out a mistake in the following sentence [ the sentence comes from 13th OG-No.91,I can't copy it directly ,and so I modify it ]:

[redacted]

Thanks.
Sincerely.
JustinCKN.

[RonPurewal]

OG is a banned source here.

this extends not only to the text of the problems, but also to discussion of the problems.

• it does not mean "let's just ask about OG problems without quoting them", as that would render the whole prohibition meaningless.

• it also does not mean "make superficial changes to the problem and then ask about it".

thank you.