从2002年起，研究生英语考试取消了语法、词汇等基础知识的考查，将此部分改考为听力。但取消了此部分知识点的考查并不意味着英语语法等基础知识的不重要。根据以往英语取得高分同学的经验和海文英语辅导名师的建议，他们都一致认为英语语法和词汇是学好、考好英语的重要基础，其实完形填空是对语法、词汇的综合考查，但更关键的是学好此部分有助于对英语句子结构的分析和理解，有助于学生掌握灵活多变的句式，这样不仅有助于学生做好阅读理解，而且有助于学生做好英译汉，写好作文。 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 been unknowingly caused by an electrici2．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
