prep07一道题求NN指点关于while用法

MarsTOF · 发表于 2011-8-3 18:27:10

Whereas the use of synthetic fertilizers has greatly expanded agricultural productivity in many parts
of the world, an increase in their use can create serious environmental problems such as water
pollution, and their substitution for more traditional fertilizers may accelerate soil structure
deterioration and soil erosion.

(A) an increase in their use can create serious environmental problems such as water pollution, and
their substitution for more traditional fertilizers
(B) an increase in their use can create serious environmental problems like water pollution, and if
substituted for more traditional fertilizers, it
(C) if these fertilizers are used increasingly, they can create serious environmental problems such
as water pollution, and if used as substitutions for more traditional fertilizers, they
(D) the increased usage of these fertilizers can create serious environmental problems such as
water pollution, while if substituted for more traditional fertilizers, this substitution
(E) the increased usage of these fertilizers can create serious environmental problems like water
pollution, while their substitution for more traditional fertilizers

答案A 纠结选项D D我知道后面的substitution有问题我主要想问while whereas 的用法。。谢谢了！！！

jameshzd · 发表于 2011-8-3 20:19:43

while 有转折的意思，另外同时有at the same time 的意思，那么通常 while 的前后两个句子时态要一致，如果说前面句子是过去式，后面的句子是现在完成时，那么显然是不能用while 的。另外D 选项用 while 是说不通的，其次是if 不要平白无故的加，原句没有用if 条件壮语从句，那么正确的选项也不会平白无故的加上if。

prep07一道题求NN指点关于while用法

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prep07一道题求NN指点关于while用法