Question

To make our city more beautiful, rubbish ________ into the river.

[　　]

A. needn't be thrown

B. mustn't be thrown

C. can't throw

D. may not throw

Answer 1

答案：B
提示：

这是含有情态动词的被动语态.首先应排除C和D，因为它们是主动语诚；含有情态动词的被动语态的构成应该是：“情态动词＋be＋及物动词的过去分词”，needn't是“不必”= don't have to ; mustn't是“禁止，不准”之意，故选B.