OG 12 41 比较中的省略问题 求解答

jiajy930809

To develop more accuratepopulation forecasts, demographers have to know a great deal more than nowabout the social and economic determinants of fertility.
A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social andeconomical
C. would have to know a great deal more than they do now about the social andeconomical
D. would have toknow a great deal more than they do now about the social and economic                                         

E. would have to know a great deal more than now about the social and economic

在prep 一题中，我曾问过类似的问题，其中一个解答是，如果要省略一起省略，要么都补出。

为什么这题不能全部省略呢？

附上上次的链接：
PREP 比较中省略问题 求解答
http://forum.chasedream.com/foru ... &fromuid=993387

brfmzbjz

在比较的结构中，原则是，前后完全一致的部分，才可以省略。
本题 they do 是绝对不可以省略的，因为它跟前面的 the would have to know 是完全不一样的时态
如果省略，则暗示比较的两边在同一时态，这是严重不合逻辑的。

同时，如果你省略了 they do, 则意思变成 a great deal knowledge 和 now 的比较
demographers have to know a great deal more than now about social and economic ...

比方，你看下面的句子：
I have to run faster than now.

看出问题了吗？

jiajy930809

brfmzbjz 发表于 2014-5-18 19:41
在比较的结构中，原则是，前后完全一致的部分，才可以省略。
本题 they do 是绝对不可以省略的，因为它跟前 ...

看出了