2013年职称英语考试语法指导：情态动词2

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2013年职称英语考试语法指导：情态动词2
情态动词+行为动词完成式
. t/ [% s/ |8 h9 _　　情态动词+行为动词完成式即“情态动词+ have + v-ed分词”，表示对过去行为或动作进行推测、评论或判断。
- k1 q6 \9 ^7 p" u* o* C　　1. must have v-ed 外语学习网
　　must have v-ed 表示推测过去某事“一定”发生了。其否定形式为：can't / couldn't have v-ed， 表示过去不可能发生某事。例如：
. q$ m* J3 F; j& D　　1）Since the ditch is full of water， it must have rained last night.
　　2）You couldn't have met my grandmother. She died before you were born.
7 [1 Z9 J) q  ~4 x  d　　2. could have v-ed
　　could have v-ed 表示推测过去某动作“很可能”发生了。例如：
　　1）“The dictionary has disappeared. Who could have taken it？”
　　2）“Tom could have taken it. He was alone yesterday.”