2016年江西成人高考高起点英语语法复习情态动词

　　(一)情态动词

　　一。情态动词的现在完成式的用法

　　情态动词现在完成式主要有两个功能：表示已经发生的情况和表示虚拟语气。在这两个方面must/mustn't，;can/cann't;need/needn't;may/mayn't;might/mightn't;should/shouldn't;

　　ougtht等情态动词+完成式表示的意思是有一定区别的

　　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 apparent the moment I walked into the room， for the first man I met asked sympathetically：“ Are you feeling all right?”

　　[A] must be [B] had been [C] must have been [D] had to be

　　(答案为C)

　　2)can't / 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 my letter; otherwise she would have replied before now.

　　[A] couldn't have received [B] ought to have received

　　[C] has received [D] shouldn't have received

　　(答案为A)

　　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 be