部分常用英语语法.docVIP

（一）．情态动词的现在完成式的用法 　　一．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/mustnt,;can/cannt;need/neednt;may/maynt;might/mightnt;should/shouldnt; 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）cant / couldnt 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] couldnt have received [B] ought to have received 　　[C] has received [D] shouldnt 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 Powers Crystal River plant, a potentially serious leakage of radioactive water may have been unknowingly caused by an electrici 　　2．表示虚拟语气。 　　1) neednt have + 过去分词，表示做了不必做的事，相当于”didnt need to do”,译为“其实没必要……”。如： 　　You neednt have come over yourself. As it turned out to be a small house party, we so formally. 　　[A] neednt dress up [B]did not need have dressed up [C] did not need dress up [D] neednt 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事情规划的很好，但实际上作者还是没有规划好，以至工作没有完成。 　　3) ought to have +过去分词，表示动作按理该发生了，但实际上未发生，译为“该……”，与should 的完成式含义类似。　　如： The porter ought to have called the fire-brigade as soon as he saw the fire in the stock, which went up in smoke . 　　4) could have +过去分词，表示过去本来可以做但却未做，译为“完全可以……”。这点与ought/should/ have +过去分词用法相似。　　如： What you said is right, but you could have phrased it more tactfully. 5) may/ might have +过去分词，表示过去可以做但实际未做，译为“（那样）也许会……”。　　如： It might have been better to include more punchy statistics and photos of equipment in the introduction to further assist fir