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题库 / Prep2007E2-SC-49
Since 1990 the global economy has grown more than it did during the 10,000 years from the beginning of agriculture to 1950.
Since 1990 the global economy has grown more than it did during the 10,000 years from the beginning of agriculture
Since 1990 the growth of the global economy has been more than that during 10,000 years, from when agriculture began
The growth of the global economy since 1990 exceeds that which had been for 10,000 years from the beginning of agriculture
The growth of the global economy since 1990 exceeds what it has been for 10,000 years, from when agriculture began
The growth of the global economy since 1990 exceeds what it did for the 10,000 years from the beginning of agriculture
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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)
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