Question

12．-They are supposed to arrive at six，but there is no sign of them．
-Something unexpected_____ to them．（　　）

• A． might happen
• B． must have happened
• C． would have happened
• D． could happen

Answer 1

分析 ---他们应该六点到，但是现在还没看见他们．
---肯定有些意料之外的事情发生了．

解答 答案：B．
结合上文可知他们还没到，故肯定猜测发生了意料之外的事情，表示对过去的事情的肯定猜测用must have done，故选B．

点评 一、"must+have+done"表示对过去事情的肯定推测，译成"一定做过某事"，该结构只用于肯定句．
1．It must have rained last night，for the ground is wet．昨晚一定下雨了，因为地面还是湿的．
2．You must have been mad to speak to the servant．你和仆人说话，一定是发疯了．
二、"can't+have+done"表示对过去事情的否定推测，译成"不可能做过某事"．
1．Mr．Smith can't have gone to Beijing，for I saw him in the library just now．史密斯先生不可能去北京了，我刚才还在图书馆见过他．
2．Mary can't have stolen your money．She has gone home．玛丽不可能偷你的钱，她回家去了．
三、"can+have+done"表示对过去行为的怀疑，用于疑问句，译成"可能做过…吗？"．
1．There is no light in the room．Can they have gone out？屋里没有灯，他们可能出去了吗？
2．There is nowhere to find them．Where can they have gone？到处找不到他们，他们可能到什么地方去呢？
四、"could+have+done"是虚拟语气，表示对过去事情的假设，意思是本来能够做某事而没有做．
He could have passed the exam，but he was too careless．本来他能够通过考试，但是他太粗心．
五、"may+have+done"表示对发生过的事情的推测，意思是"可能已经"或"也许已经"，用于肯定句中．
-What has happened to George？
-I don't know．He may have got lost．
-乔治发生了什么事？