英语辨析(must be;might be……)

英语辨析(must be;might be……)
求must be;might be;can't be;may be;;may;might;could;must;can't的含义,用法,词性,辨析等.

have to和must1) 二者在肯定句中一般可以互换,表示不可逃避的义务或责任.但must(必须）更带有说话人的主观色彩,而have to（不得不）则更强调客观要求和外界影响.I must work hard to earn more money 我一定要赚更多的钱.I have to work hard to earn more money 我不得不赚更多的钱.2) have to有人称、数、时态的变化,而must只有一种形式.
He had to look after his sister yesterday.在过去时的句子中must要改成had to She had to go shopping yesterday.
3） 在否定结构中：don't have to 表示"不必" mustn't 表示"禁止",have to 的否定形式是don’t have to,相当于needn’t
You don't have to tell him about it.你不必把此事告诉他.
You mustn't tell him about it.你禁止把这件事告诉他.
Must you leave now?No,I needn’t./ No,I don’t have to.不,我不必.Yes,I must./ Yes,I have to.是的,必须.
4) must表示推测,have to不可以 must用在肯定句中表示较有把握的推测,意为"一定".对现在或未来的事进行猜测时,must 后面通常接系动词be 的原形或动词的进行式.It must be that naughty boy crying outside .肯定是那个调皮的孩子在外面大叫.The idea must be accepted [��k'septid] by the society [s��'sai��ti] sooner or later.这种想法肯定迟早会被社会所接受的.You have worked hard all day.You must be tired.你辛苦干一整天,一定累了.（对现在情况的推测判断）
He must be working in his office.他一定在办公室工作呢.对已经发生的事进行猜测时,must + have + 过去分词.It must have rained last night for it is so wet outside .外面这么湿,昨晚肯定下雨了.I didn't see you in class yesterday.You must have been absent .我昨天上课没见着你,你肯定没有来.
比较He must be staying there他现在肯定待在那里.He must stay there.他必须待在那里.The light is still on,so he must be at home.灯还是亮的,他一定在家.The light was out.They must have gone to bed.灯都熄了,他们必定睡了.5)must表示推测时的否定式是can’t或couldn’t(不可能) ,因为must只用于肯定句,语气很强.If Tom didn't leave here until five o'clock,he can't be home yet.　如果汤姆五点才离开这儿,他此时一定还未到家.
6) have to 与have got to 在表示不得不时,可以互换.can 和 may 1.can（过去式为 could）原义为“能”,表示“有能力”、“能够”等：Can you drive a car?你会开车吗?Jim couldn't run very fast when he was a boy.吉姆小时候不能跑很快.2.can/could/may/might表示请求或允许,多用于口语中,意为“可以、能”等.这里could / might 是代替can/may 的一种比较委婉地提出请求的方法.时间上是现在时.如：　　　You can/could/may/might go home now.现在你可以回家了.You can/could/may/might go to the cinema this evening.你今晚可以去看电影.-- Can/　Could/　May/　Might I use your ruler?我可以用一下你的尺子吗?Of course you can/may.你当然可以.（不可用could或might）Yes,please./ Certainly [��s��:tnli] / Of course.等.这些肯定答语显得热情、客气.否定：No,you can't/may not.不,你不可以.（不用could not或might not） 拒绝对方时,其答语可以用 No,you mustn’t./ No,you can’t.或 Sorry,you can’t./ No,please don’t.等说法.3.may和might还可以表示可能.如果说话人对所说事实确信无疑,就可以用be或其他动词原型：Jane is at home now.简现在在家.（确切的事实） 但如果不敢确定,则可以说：Jane may/might be at home.简可能/或许在家.He may/might know you.他可能认识你.The may/might go to the Great Wall next week.他们可能下周去长城. 　　注意：在否定句中一般不用 may not ,常用 can’t 表示“不可能”.例如：　　He can’t be at home tonight.今晚他不可能在家. 说话的人说的是现在可能发生的事情用 may + do the play may begin at any moment .剧可能马上就要上演了.可能已经发生的事情用may+have+done It may have begun already.可能已经开始了.　　4.用于特殊疑问句中,表示不确定,常可译为“会”.Who may call me at night?谁会在晚上给我打电话呢?　　5.表示希望、祈求、祝愿,常可译为“祝愿”.如：　　May you have a good time.祝你过得愉快.　　May you be happy!May+ 想要做的事情 May that day come soon.6.may/might as well 还是 的好 不是很情愿,但考虑之后,还是这样做了.He will never pass.He might/may as well give up.内容提供 菁英网上英语