B) 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:
- 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)

C) first, you've got a "which" modifier that isn't preceded by a comma, so that's an automatic failure. (note that you can use preposition + which without a comma -- e.g., the box in which you placed your valuables -- but you cannot do so with just plain "which".)
more importantly, "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.

D) you can't use the present perfect if the time interval is over. If the trend continues into the present day, then the present perfect is appropriate.
Even if that were fixed, choice D still suffers from fatal wordiness / lack of concision, especially in comparison to the correct choice."

E) 'what it did' doesn't make any sense:
* the growth didn't 'do' anything
* there's no other verb to which 'did' could logically be parallel to complete the comparison

In general,

1 * if you have than/as + subject + FORM OF "TO BE" as the second half of a comparison, then you must have another form of "to be" in the first half of the comparison.
or, there should be something in the first half that would make sense with "to be" in front of it.

2 * if you have than/as + subject + HELPING VERB as the second half of a comparison, you can have just about any other form of the same verb in the first part, as determined by context.

3 * if you have than/as + subject + FORM OF "TO DO" as the second half of a comparison, then you must have an ACTION VERB[/b] (or another form of "to do") in the first half of the comparison.

here are some examples:
#1
the air quality of las vegas is higher this year than it was in 2005.
parking spots are disappearing much more quickly today than they were yesterday.
#2
james can negotiate with salespeople more effectively than stephanie can. (comparing their abilities)
james can negotiate with salespeople more effectively than he does. (his ability exceeds his actual performance, probably because he just isn't trying very hard)
#3
parking spots disappeared much faster today than they did yesterday.
tanya eats more slowly than she did when she was a teenager. (note that "did" doesn't have to have the same tense as the action verb)

Choice C – This choice has verb tense error. Element 2 uses past perfect tense. Whenever past perfect tense is used, there should be a related event in simple past tense to indicate the intended sequencing of event. In this sentence there is no such event and hence use of past perfect tense is incorrect. Furthermore, this choice appears to be wordy. Two relative pronouns referring to same noun – growth seems wordy.

In general,

1 * if you have than/as + subject + FORM OF "TO BE" as the second half of a comparison, then you must have another form of "to be" in the first half of the comparison.
or, there should be something in the first half that would make sense with "to be" in front of it.

2 * if you have than/as + subject + HELPING VERB as the second half of a comparison, you can have just about any other form of the same verb in the first part, as determined by context.

3 * if you have than/as + subject + FORM OF "TO DO" as the second half of a comparison, then you must have an ACTION VERB[/b] (or another form of "to do") in the first half of the comparison.

here are some examples:
#1
the air quality of las vegas is higher this year than it was in 2005.
parking spots are disappearing much more quickly today than they were yesterday.
#2
james can negotiate with salespeople more effectively than stephanie can. (comparing their abilities)
james can negotiate with salespeople more effectively than he does. (his ability exceeds his actual performance, probably because he just isn't trying very hard)
#3
parking spots disappeared much faster today than they did yesterday.
tanya eats more slowly than she did when she was a teenager. (note that "did" doesn't have to have the same tense as the action verb)

B) 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:
- 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)

C) first, you've got a "which" modifier that isn't preceded by a comma, so that's an automatic failure. (note that you can use preposition + which without a comma -- e.g., the box in which you placed your valuables -- but you cannot do so with just plain "which".)
more importantly, "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.

D) you can't use the present perfect if the time interval is over. If the trend continues into the present day, then the present perfect is appropriate.
Even if that were fixed, choice D still suffers from fatal wordiness / lack of concision, especially in comparison to the correct choice."

E) 'what it did' doesn't make any sense:
* the growth didn't 'do' anything
* there's no other verb to which 'did' could logically be parallel to complete the comparison

考查要点是代词和比较结构
A Since 1990 the global economy has grown more than it did during the 10,000 years from the beginning of agriculture
比较结构是the global economy has grown more than the global economy(it整体指代) grew
合理
且后面from...to...也是平行结构，beginning和1950相较于when和1950更好
B Since 1990 the growth of the global economy has been more than that during 10,000 years,from when agriculture began
错选B
比较结构是the growth of the global economy has been more than the growth(that) during 10,000 years is
根据Ron所说，that+prep在比较结构中最好严格与前方平行，所以前方也应该有growth during之类的对照
其次，the growth is more than growth is 并不好，不如faster than the growth is
最后，when和1950不如beginning和1950平行

C The growth of the global economy since 1990 exceeds that which had been for 10,000 years from the beginning of agriculture
没有使用had been的标志词；
which不能不加“，”,除非是介词+which的形式（存疑）
had been与前半句无对应，应该是前半句有be的内容，后半句才能有had been这种省略

D\E中it完全指代，后半句根本不成逻辑

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)

B选项 that若用来指代growth，则前半部分缺少一个时间段去和后面的during...平行；根据Ron的解释，from When（名词从句）没有问题，只是跟the beginning （完美的名词）比起来欠佳。

B growth是个名词， 不能用more来形容。可以说 grow more但不能说growth is more。growth应该是higher
C 不用had been。句子里没有过去式标志
D 不用has been，过去那段时间的增长对现在没有影响了
E it did有问题，did在前面没有比较对应

时态的问题可以eliminate C，D；E选项的what it did有问题，这里的it 指的是the global economy 但是 the global economy处于介宾短语中，是不能指代的；B选项的that during也是有点问题，这是一个平行结构的标志，前面的部分要和后面的that + preposition平行

an actual noun is almost always superior to a circuitous noun clause, when possible
when it began VS the beginning of...

from when agriculture began❌

A，主语是全球经济，没有限定是什么是什么时候的全球经济，Since 1990作状语修饰has grown，后面用it指代全球经济是可以的；如果是全球经济since 1990则后面只能用that

from when是错误表达

E：it指代The growth of the global economy，原则上应该指代global economy

A，主语是全球经济，Since 1990作状语修饰grown，后面的it指代全球经济ok。如果since 1990作定语修饰全球经济，则it存在同物指代的问题。
B，since 1990作状语修饰 the growth has been more，语意是：自从1990年以来，经济增长比农业开始以来的1000年的经济增长还要多。不是自1990年来就一直多，而是自1990年来的经济增长比之前1000年的增长总和还要多。

1、do sth during……表示在一个时间范围里发生某动作，for回答how long的问题，不代表完成时态；
如：
Please remain seated during the performance.
There are extra flights to Colorado during the winter.
I'll stay here for a week.
同理，economic grow during 10000 years要比 for 10000 years好
2、Higher/lower Growth，grow faster/more slowly

since 1990是介宾短语，做状语，B的Since变成修饰more than， 错，应该修饰grow

C - 过去完成时错；D - 现在完成时错； E- it指代错误

they, their, it都是完整指代，即指代包含了被指对象的所有修饰成分， that， one都是核心指代。