这教室能坐三十位学生。 The classroom can seat thirty students,

你必须遵守校规。You must obey the school rules,

屋里很冷，他们肯定把暖气关了。It is cold in the room,They must have turned off the heating,

地湿了，昨晚肯定下雨了。It must have rained last night,The ground is wet,

地湿了，昨晚可能，也许下雨了。It may have rained last night,The ground is wet,

 It might have rained last night,The ground is wet,

 It could have rained last night,The ground is wet,

 你看见的是什么？我不能说。What was the something you saw?  I couldn't say,

 你不能说还是你不愿意说？You couldn't say or you wouldn't say?,

shall在纯表示将来的陈述句中只用于第一人称。

在问句中征求对方的意见和指示的时候常用于第一、三人称。

要我帮你寄信吗？Shall I post your letter for you?,

我们帮你拿行李好吗？Shall we carry your baggage?,

亨利在外面等着。他要不要进来？。Henry is waiting outside, Shall he come in?,

用于第二、三人称，表示说话人的许诺、命令、警告、威胁或允诺等。

告诉杰瑞，如果他好的话，他会得到一份礼物。Tell Jerry that he shall get a gift if he is nice,

你的所作所为应该受到惩罚。 You shall be punished for what you've done,

should构成过去将来时作为shall的过去时。

他问我今晚是否有空。He asked me whether I should be free tonight,

should,表示主语的义务或责任。

你不应该在两餐之间吃东西，因为这会使你发胖。 You shouldn't eat between meals, for it will make you fat,

should,表示很大的可能性，常译为“按道理说应该”。

“游泳”一词中应该有一个双“m”。There should be a double ‘m’ in the word ‘swimming’,

 should用于否定句、疑问句表示“竟然”，含意外、惊异、愤怒、失望等语气。

你今天为什么要这么晚？。Why should you be so late today?,

我不明白你为什么认为是我干的。I don't understand why you should think that I did it,

should,在if, 从句中表示“万一”。

如果你要见汤姆，请他给我打电话。Ask Tom to ring me up if you should see him,

 表示过去没有做到本来应该做的事情should have done,

 做了本来不应该做的事情shouldn't have done,

你应该给他更多的帮助。You should have given him more help,

你不应该一句话也不说就离开家。You shouldn't have left home without saying a word,

can,或者could,表示能力。

他英语讲得比你好。 He can speak English better than you,

can,和be able to,都可表示能力，两者在意思上没有什么区别。

can,只能有现在式和过去式could,，

be able to,则有更多的形式，可位于情态动词之后表达过去成功地做了某事。

他将能把工作做得更好。He will be able to do the work better,

他能够按时完成工作。He was able to finish the work on time,

can,或者could,表示客观的可能性，也可以表示一时的情况，意为：有时候会。

任何醉酒的司机都可能发生事故。Accidents can happen to any drunken driver,

根据广播，今天下午可能会下雨。According to the radio, it could rain this afternoon,

这里夏天可能很热。It can be very hot here in summer,

表示“许可”时can,可以和may,换用，

如果要表示语气婉转，可用could,代替can,，这时could,不再是can,的过去式，注意回答时不能用could,，而用can,。

你现在可以回家了。 You can go home now,

You may go home now,

你明天能再来吗？是的，我能。Could you come again tomorrow?Yes, I can,

can,在疑问句和否定句中表示推测、怀疑、惊奇、不相信的态度。

这辆绿色自行车是刘东的吗？Can this green bike be Liu Dong's?,

你怎么能相信像他这样的骗子？。How can you believe such a liar like him?,

 could have done,有虚拟的含义，即“本来能够做，但事实上却没有做”。

你本可以早点告诉我的。You could have told me earlier,

我本可以帮助她。I could have helped her,

如果我更加努力的话，我本可以通过考试的。I could have passed the exam if I had worked harder,

may,或者might,表示允许或许可，否定用mustn't, 表禁止。

我们可以在这个湖里游泳吗？不，你不能。太危险了。 May we swim in this lake? No, you mustn't, It's too dangerous,

may,或者might,肯定可以用比较婉转的说法进行回答。

我可以用这本字典吗？ May I use this dictionary?,

是的，请。Yes, please,

当然Certainly,

是的，你可以。Yes, you can,

may,或者might,在表示请求时，用might,比may, 语气更婉转些,

我可以看看你的新电脑吗？ May I have a look at your new computer?,

注意：May I?在文体上较正式，较客气，日常口语中常用Can I?

may,或 might,都可以表示可能性，表示“或许”、“可能”之意，might,表示语气更加不肯定，

他们现在可能在图书馆里。They may be in the library now,

 They might be in the library now ,

他缺席了。他可能病了。He is absent, He may be ill,

 He is absent, He might be ill,

出发晚的人可能会粗心驾驶，The person who sets out late might be careless in driving,

The person who sets off late might be careless in driving,

“某一事件在过去发生的可能性”。may have done,

她为什么没来？Why hasn't she come?,

她可能没赶上火车。She may have missed the train,

虚拟的含义，表示“与事实相反”。might have done,

你爬上去太愚蠢了，你可能会自杀的。You were stupid to try climbing up there, You might have killed yourself,

May,用于祈使句，表示祝愿。

祝你有一个幸福的生活。May you have a happy life,

祝你成功。May you succeed,

祝你新年快乐。 Wish you a happy new year,

祝你成功。Wish you success,

我们祝您事业成功。We wish you success in your new business,

must,表示“必须”、“应该”之意，语气比should, 或者ought to,强烈， 其否定式 must not,，缩写形式为 mustn't,，表示 “不准”、或“禁止”之意，

我们必须努力学习，每天进步。We must study hard and make progress every day,

你不能碰火。 You mustn't touch the fire,

对以must,提出的疑问句，如作否定回答时，要用needn't,或者don't have to, (不必)来回答，而不用mustn't,，因为mustn't,表示的是“禁止”或“不许可”之意，

我们必须明天完成这项工作吗？Must we finish the work tomorrow?,

不，你不必，但你必须在三天内完成，No, you needn't, but you must finish it in three days,

No, you don't have to, but you must finish it in three days,

Must,可以表示推测，表示“一定”或“必定”之意，只用于肯定句中。

它会是谁的新自行车？那一定是刘东的，我知道他父亲刚刚给他买了一个新的。Whose new bike can it be? It must be Liu Dong's, I know his father has just bought him a new one,

你一定病了，我从你的脸上看出来。You must be ill, I can see it from your face,

 用于对过去或已经完成的事情的推测。must have done,

 用于对现在正在进行的事情的推测。must be doing,

 外面一定在下雨。It must be raining outside,

 你已经浏览过这篇文章了，是吧？He must have gone over the article, hasn't he?,

must,侧重表示说话人的主观看法，have to, 则表示客观需要

 我必须要求你再也不要那么做了。 I must ask you not to do that again,

孩子，如果你想要抓住鱼，你必须像鱼一样思考。Son, if you want to catch a fish, you have to think like a fish,

你必须在下周一之前交作文。You have to hand in your compositions before next Monday,

have to, 有人称、数和时态的变化,否定式要用助动词，don't have to,

他们不得不加快速度，因为天气变得很糟糕。 They had to speed up, for the weather turned terrible,

他因病不得不呆在家里He has to stay at home because of illness,

will, 可以表示“意志”或“决心”

我一再告诉他戒烟，但他不听。 I have told him again and again to stop smoking, but he will not listen,

有人能帮我吗？我会的。Can someone help me? I will,

will, 请求或询问对方的意愿，

请问去首都体育馆怎么走？ Will you please tell me how to get to the Capital Gymnasium?,

你能打开窗户吗？Will you open the window?,

will, 表示一种习惯性或某种倾向的动作，有“总是”或“惯于”之意，will, 指现在，would, 指过去。

 每天早上他都会沿着这条河散步。Every morning he will have a walk along this river,

鱼离开水就会死去。Fish will die out of water,

否定形式won't,还可以表示“某事没有达到我们期望的效果”。

 车启动不了。The car won't start,

 门打不开。The door won't open,

would,作为will,的过去式，可用于各人称，表示过去时间的"意志"或"决心"

他答应再也不抽烟了。 He promised he would never smoke again,

would,在疑问句中，用于第二人称，表示说话人向对方提出请求或许问对方的意愿时，比用will,更加婉转，

你想再来点咖啡吗？Would you like some more coffee?,

在日常生活中，常用“I would like to,”表示“我想要”或“我愿意”之意，以使语气婉转，

尽管我想留下来，但我确实必须回家。Much as I would like to stay, I really must go home,

虽然;尽管much as,

would,可以表示过去的习惯动作，比used to,正式，并没有“现已无此习惯”的含义。

去年，我们的英语老师有时会在课后用英语给我们讲故事。Last year our English teacher would sometimes tell us stories in English after class,

假期期间，他每周都来看我。 During the vacation he would visit me every week,

would, 料想或猜想，

他离家时大约十点。It would be about ten when he left home,

她会在那里干什么？What would she be doing there?,

我以为他会告诉你的。I thought he would have told you about it,

need,作情态动词用时，主要用于否定句和疑问句中，

他现在不必为我们担心。He needn't worry about us now,

你现在需要走吗？是的，我必须。Need you go now?Yes, I must,

need,也可作为行为动词用，有时态和人称的变化，可用于肯定句、否定句和疑问句中，其后可接名词、代词、动名词或带to的动词不定式为其宾语。

我需要你的帮助。I need your help,

你需要每天练习朗读。You need to practise reading aloud every day,

 你不必马上去修车。You don't need to have the bike repaired right away,

needn't,后接完成式可以表示过去做了一件本来不必要做的事情，

你昨天回信了吗？是的，我做了。Did you answer the letter yesterday? Yes, I did,

但你不必回答。But you needn't have answered it,

 我不需要去车站。(我没有去)I didn't need to go to the station,

 我本来不需要去车站。(实际上我去了)I needn't have gone to the station,

dare ,或者dared, 作情态动词用时，主要用于否定句，疑问句，if,或者whether, 引出的宾语从句和条件从句中，

他敢再违反交通规则吗？Dare he break the traffic regulations again?,

如果你敢做这样的事，你会受到惩罚的。You will be punished if you dare do such a thing,

dare,常用作行为动词，其变化与一般行为动词相同，

她敢于晚上独自呆在家里。She dares to stay at home alone at night,

谁敢去？我不敢去。Who dares to go? I don't dare go,

Who dares to go? I don't dare to go,

I dare say,作插入语，“我想，大概，可能，或许”。

你不必告诉他，因为我早就告诉他了。You needn't have told him, for I had told him about it earlier,

我们应该为前门买一把新锁。We should have bought a new lock for the front door,

我不确定明天下午我是否会去听讲座，我可能会去布莱克教授的课。I'm not sure that I'm going to the lecture tomorrow afternoon, I might go to Prof Black's class instead,

I'm not sure that I'm going to the lecture tomorrow afternoon, I may go to Prof Black's class instead,

我没有听到铃声，我一定是睡着了。I didn't hear the bell ring, I must have been asleep,

一条狗跑到我母亲的车前，她不得不很快停下来。A dog ran in front of my mother's car and she had to stop very quickly,

你本该早点到的。You should have arrived earlier,

You ought to have arrived earlier,

她一定把桌子擦干净了，因为桌子很干净。She must have cleaned the table, for the table is very clean,

你能屏住呼吸5分钟吗？  Can you hold your breath for 5 minutes?,

 导游建议我们今晚出发，The guide suggested that we should set off tonight,

 The guide suggested that we should set out tonight,

你应该原谅她，因为这不是她的错。You should forgive her, for it is not her fault,

我们不能嘲笑老人。We mustn't laugh at the old people,

油会浮在水面上。Oil will float on water,

她不能来了，因为老板今天要她完成很多工作。She can't turn up, for her boss asked her to finish a lot of work today,

这可能是一种习惯。It may be a custom,

她过去常捉弄别人。She used to play a trick on others,

还有20分钟，我们不必这么着急。 There is 20 minutes left, We needn't have to be in such a hurry,

他在战争爆发前逃离了欧洲。He was able to flee Europe before the war broke out,

彼得今晚可能和我们一起来，但他不确定。Peter may come with us tonight, but he isn't sure,

我的朋友约翰过去抽烟，但现在不抽了。My friend John used to smoke, but now he doesn't,

 我妈妈今天早上应该叫我，但她没有，所以我上学迟到了，受到老师的责备。My mother should have called me this morning, But she didn't, so I was late for school and was blamed by my teacher,

他们必须尽快完成这个任务They must finish the task as quickly as possible,

外国也能将它们的节目传送到中国来。Foreign countries can send their programs to China,

相信我的话，我一定让你们平安到达利物浦。Upon my word, I will land in Liverpool,

应当首先满足世界人口的基本需要。The basic needs of the world's population must be satisfied first,

 The basic needs of the world's population must be met first,

以前这里有个公园。There used to be a park here,

已经六点了。你随时都该到这儿。It's six o'clock now,  He should be here at any moment,

没有图书管理员的许可不得把书拿出图书馆。No reader shall take a book out of the library without permission of the librarian,

从他脸上担心的表情判断，我们知道他一定是有了麻烦。Judging from his worried face, we knew that he must have had some trouble,

表示对过去事情的很肯定的推测。must have done,