情态动词有must, can, may, need, dare, ought(to), should等。情态动词和一般助动词的区别是情态动词有一定词义,它和另一动词构成谓语。考生尤其要注意情态动词接不定式的完成式和其他一些特殊的用法。

　　例1: Mary my letter; otherwise she would have replied before now.

　　A. has received B. ought to have received

　　C. couldn't have received D. should have received

　　[答案] C. couldn't have received

　　[注释] "couldn't+完成时不定式"表示对过去行为的否定推测。

　　[译文]玛丽不可能收到我的信的；否则她早就给我回信了。

　　例2: Carey didn't go to the party last night because she the baby for her sister until 9:30.

　　A. must have looked after B. would have to look after

　　C. had to look after D. should have looked after

　　[答案] C. had to look after

　　[注释]主句用一般过去时，原因从句中也用一般过去时。

　　[译文] Carey昨晚没有去参加聚会，因为她得为她姐妹照看小孩到9:30。

　　例3: I regretshavingsleft the work unfinished; I everything ahead carefully.

　　A. should plan B. should have planned

　　C. must plan D. must have planned

　　[答案] B. should have planned

　　[注释] should have done sht.表示过去本来应该做而实际上没有完成的行为动作或状态。

　　[译文]我后悔把工作半途而废；我本来应该事先仔细把每件事安排好。

　　例4: From the tears in Nedra's eyes we can deduce that something sad .

　　A. must have occurred B. would have occurred

　　C. might be occurring D. should occur

　　[答案] A. must have occurred

　　[注释] "must+完成时不定式"表示对过去行为的肯定推测。

　　[译文]从Nedra眼中的泪水我们能推断，一定发生了什么悲伤的事。

　　例5: The millions of calculations involved, had they been done by hand, all practical value by the time they were finished.

　　A. could lose B. would have lost

　　C. might lose D. ought to have lost

　　[答案] B. would have lost

　　[注释]本题虽测试虚拟语气的用法,但3个干扰项都涉及到情态动词的含义及用法。

　　[译文]有关的数以百万次的计算，如果用手工进行，到它们完成时就失去了全部实用价值。

　　例6: My pain apparent the moment I walkedsintosthe 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] C. must have been

　　[注释] must与完成时不定式连用往往表示对过去发生的事情的主观推测，常译为"一定是……"。

　　[译文]我走进房间时我的痛苦显而易见，因为我遇到的第一个人同情地问我："你现在感到好点吗？"

　　例7: 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

　　[答案] D. needn't have dressed up

　　[注释] "needn't+have+过去分词"表示过去本来不必做的事情，而实际上做了。turn out to be意为"结果是"。

　　[译文]由于这原来是一次小型家庭聚会，我们本来就没有必要穿得那么正式。

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