考研英语语法10 天速成 （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;ought 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 been unknowingly caused by an electrician. 2．表示虚拟语气。 1) needn’t have + 过去分词，表示做了不必做的事，相当于”didn’t need to do”,译为“其实没必要……”。如： You needn’t have come over yourself. As it turned out to be a small house party, we so formally. [A] needn’t dress up [B]did not need have dressed up [C] did not need dress up [D] needn’t have dressed up (没有必要穿的那么正式，体现是说话者的建议，实际结果是否真的穿的很正式没有确定，答案为D) 2）should have +过去分词，表示应该做某事但实际上未做，译为“本应该……”should not + have 过去分词表示本不应该做某事但实际上做了，译为“本不应该……”。如： I regret having left the work unfinished; I should have planned everything ahead carefully. 我本来应该事先认真地把每件...
