Question

【题目】Since nobody gave him any help, he __________ have done the research on his own.

A. can B. must

C. would D. need

Answer 1

【答案】B

【解析】句意:因为没有人帮助他，他一定独自完成了这项研究。must表示肯定的推测，意为“一定”；符合句意。can表示推测时,常用于否定句和疑问句； would have done表示对过去已经发生的情况的不太确定的推测；need必要。