江西成人高考高起点英语语法归纳与练习

    英语语法归纳与练习

    （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 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 c