一、情态动词表推测的三种形式1.情态动词+动词原形,表示对现在某动作或状态的推测,比如must do,can’t be等。例:It can’t be true.这不可能是真的。2.情态动词+动词进行式,表示推测某动作可能正在进行,比如must be doing等。例:Lily must be doing her homework now.莉莉现在一定是在做作业。3.情态动词+动词完成式,表示对过去行为或动作的推测,比如must have done等。例:He must have misunderstood me.他一定是误解了我。
二、情态动词表推测的具体含义不同的情态动词与行为动词搭配,其具体含义会有所不同。这里,我们主要针对"情态动词+have done"结构,详细讲解其含义。
1.must have done:推测某事必定已经发生,只用于肯定句,否定形式用can’t have done。例:The light is on.Father must have come back.灯亮着,爸爸一定已经回来了。
2.could have done:对已发生的事的可能性进行推测。例:The dictionary has disappeared.Who could have taken it?字典不见了。会是谁拿了呢?could have done还可以表示某事本来可能发生却未发生。例:I could have slept for long,but Ididn’t.我本来可以睡的时间长一点儿,但是我没有。
3.can’t/couldn’t have done:表示某事不可能已经发生,couldn’t have done语气更委婉。例:She can’t have gone to school.It’s Sunday.她不可能去上学了。今天是星期天。
4.may/might have done:推测某事可能已经发生,might have done所表示的可能性更小。例:Polly is very late.She may have missed her train.波莉到现在还没有来。她可能是误了火车。
5.should/ought to have done:表示某事本?该发生却未发生,含有责备、遗憾的意味。例:She should have arrived here by now.她现在应该已经到这儿才对啊。6.shouldn’t/oughtn’t to have done:表示某事本不应该发生却已经发生,含有责备的意味。例:You oughtn’t to have spoken to them in that way.你不应该以那种方式对他们讲话。7.need have done:表示过去有必要做却没有做,含有责备的意味。例:You need have practiced your spoken English more often.你本来应该多练习英语口语的。8.needn’t have done:表示做了不必要做的事。例:There was plenty of time.She needn’t have hurried.那会儿时间还很多,她没必要那样匆忙。
表推测时,英语中只使用must,may,might,may not和can’t。这五个表达的语气依次递减:
must:一定(语气肯定)
may:也许(不很肯定)
might:或许(比may语气更弱)
may not:也许不(表否定)
can’t:一定不(must的反义)
推测现在的事情用must,may,might,may not和can’t+do或be
e.g.She must be at home now.
The boy may play now.
推测过去的事情用must,may,might,may not和can’t+have done
e.g.She might have been ill yesterday.
He must have hold the party.
注意:表推测的must,may,might,may not和can’t是不可以与I think...连用。因为I think...已有推测的含义,故不能连用。