2012考研必备:考研英语语法精要(21)
七、情态动词注意情态动词完成式的用法有两方面的含义:
1.表示已经发生的情况
(1)must have +过去分词,表示对已发生情况的肯定推测,译为“(昨天)一定……”。如:
My pain must have been apparent the moment I walked into the room, for the first man I met asked sympathetically: “Are you feeling all right?”
(2)cant/couldn’t have +过去分词,表示对已发生情况的否定推测,译为“(昨天)一定没……”。 如:
Mary couldn’t have received my letter; otherwise she would have replied before now.
(3)may/might have +过去分词,表示对已发生的事情做不肯定、可能性很小的推测,或事实上根本没发生,译为“也许……”。如:
At Florida Power’s Crystal River plant, a potentially serious leakage of radioactive water may have been unknowingly caused by an electrician.
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