问问GWD13-41

The spraying of pesticides can be carefully planned, but accidents, weather conditions that could not be foreseen, and pilot errors often cause much larger deposits of spray than they had anticipated.

A.      weather conditions that could not be foreseen, and pilot errors often cause much larger deposits of spray than they had

B.       weather conditions that cannot be foreseen, and pilot errors often cause much larger deposits of spray than

C.      unforeseeable weather conditions, and pilot errors are the cause of much larger deposits of spray than they had

D.      weather conditions that are not foreseeable, and pilot errors often cause much larger deposits of spray than

E.       unforeseeable weather conditions, and pilot errors often cause much larger deposits of spray than they had

答案选B

我选E

B中的从句肯定没有E的形容词简洁，但是这只是有效性的问题。E的they没有指代对象。

为什么不选D呢？

情态动词优先

句子，but A,B,and C often cause... than they had done

比较对象前 cause 用一般现在时，比较对象后面的句子肯定不为过去完成时，排除A,C,E

情态动词不能随便改变，排除D

the correct answer is: B