【题目】Eight months ought to be enough for you to finish this paper, ____________?
A.oughtn't they
B.didn't they
C.shouldn't it
D.shouldn't they

【答案】C
【解析】句意：八个月对你完成论文应该足够了，是吗？陈述句中含有情态动词ought to时，附加疑问部分既可以使用oughtn't+主语，也可以使用shouldn't+主语；又因＂八个月＂表示一段时间，为单数，要用it指代。故选C。