(2013·济南一中模拟)—Where Mary have put the empty bottles?
—She them away. They must be somewhere.
A. can; can't have thrown
B. must; needn't
C. must; must have thrown
D. can; mustn't have thrown
网友回答
(答案→)A. can; can't have thrown
B. must; needn't
C. must; must have thrown
D. can; mustn't have thrown
解析：选A 句意：“玛丽可能把空瓶子放在什么地方了？”“她不可能扔掉，瓶子一定在某个地方。”第一空在疑问句中表示可能性用can；第二空表示“不可能做过某事”用can't have done，注意不能用mustn't表示推测。