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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 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 first-time office automation managers.

 

来源:中国教育在线
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