情态动词+ do

 你不该这样粗心大意。You shouldn't be so careless

 杰西卡昨天告诉他，她可能不去旅行了。Jessica told him yesterday she might not go on the trip

 困难能够而且必须克服。Difficulties can and must be overcome

情态动词+ be doing

 她肯定在听流行音乐。She must be listening to pop music

 你应该在复习功课。You should be reviewing your lessons

 我妈妈可能正在做饭。My mother may be cooking now    

 My mother might be cooking now

情态动词+ have done

 他们可能参观过长城了。They might have visited the Great Wall

 他一定起得很早去赶火车了。He must have got up very early to catch the train

 你本该早一点儿来。You ought to have come earlier

情态动词+ be done

 这个词也可以用作动词。This word can also be used as a verb

 必须采取措施来制止污染。Something must be done to stop pollution

 这工作早就该完成了。The work ought to have been finished long ago

 情态动词第三人称单数一般现在时没有词形变化。

 你应该穿件雨衣。You ought to wear a raincoat

 她应该穿件雨衣。She ought to wear a raincoat

 为了存活植物必须有氧气。Plants must have oxygen in order to live

 为了存活植物必须有氧气。a plant must have oxygen in order to live

 情态动词的时态并不是区分时间的主要标志。在一些场合中，情态动词的现在式和过去式都可以表示现在时间、过去时间或将来时间。

 我看今晚可能要下雨。I'm afraid it might rain tonight

 我可以借用你的暖水瓶吗？Could I borrow your thermos?

 今天天气不错，我们可以出去散散步。it 's a nice day today, We could go for a walk

 情态动词是互相排斥的，一般不允许两个意义相近的情态动词连用。

 军人必须服从命令。Soldiers have to obey orders

 军人必须服从命令。Soldiers must obey orders

 我能一次借两本书吗？Can I borrow two books at a time?

 我能一次借两本书吗？Will I be able to borrow two books at a time?

在口语中可用 can,  could 代替 may ，但在正式场合用 may 。表示允许时，也可用 might 代替， might 不表示过去时，而是表示口气比较婉转。

 如果你喜欢可以坐这个位置。You may take this seat if you like

我可以和你谈谈吗？May I have a talk with you ?

 Can I have a talk with you ?

  Could I have a talk with you ?

 Might I have a talk with you ?

我可以进房间看我母亲吗？May I come into the room to see my mother ?  

  Might I come into the room to see my mother ?

 不，你不能进。她需要好好休息。 No,  you mustn't ,  She needs to have a good rest

 是的 请。Yes，  please

 当然可以。Certainly

 是的 当然。Yes，  of course

 确定。Sure

 请接着讲。Go ahead，  please

 不 你不能。No,  you can't

 不 你一定不能。No,  you mustn't

 请不要。你最好不要。Please don't,  You'd better not

 我认为你不能。I don't think you can

 我很抱歉这是不允许的。I'm sorry it 's not allowed

表示推测，可译为“可能，也许”。

 你们的数学老师可能在办公室里。Your math teacher may be in his office   

 Your math teacher might be in his office

一般情况下， might 表示的可能性很小

 那盏灯没有亮，它可能坏了。The light isn't on  it might be broken  

 The light isn't on  it may be broken

 瓶子里也许还剩点儿墨水。There may be some ink left in the bottle   

   There might be some ink left in the bottle

用 may 表示推测一般不用于疑问句，在疑问句中通常用 can 来代替。

 他可能在家吗？Can he be at home?

 这可能是真的吗？ Can it be true?

 可能是，也可能不是。 it may be,  or may not be  

用在目的状语从句中，构成谓语。

 他想坐出租车，这样他就能及时到达那里。He wants to take a taxi so that he may get there in time

 我早早地就到了机场为了能接到他。I arrived at the airport earlier in order that I might meet him

有时可以用于祈使句表示祝愿。

 祝你成功May you succeed

 祝你快乐。May you be happy

 希望这一天早日到来。May that day come soon

表示能力，可译为“能，会”。

 我会游泳。I can swim

 艾米丽舞跳得很好，她妈妈年轻时舞跳得也很好。Emily can dance well and her mother could dance well when she was young

 这电影院能容纳一千人。The cinema can seat one thousand people

 我七岁时连如此简单的书我也看不懂。 I could not read such an easy book when I was seven years old