1needn't 意为“不必”。如：You needn't meet him unless you'd like to.你不需要见他，除非你愿意。
2needn't+have+动词的过去分词，表不需要完成但已完成的动作，暗含时间或精力上的浪费。
如：You needn't have bought it. 你没必要买它（但你却买了）。
5.shouldn't表示不应该。
如：You shouldn't feel so unhappy over such little things. 对于这种小事，你不应该感到这么不高兴。
04
情态动词的被动语态
含有情态动词的被动语态的结构为：情态动词+be+done动词的过去分词。
做题时要兼顾情态动词和被动语态这两个方面。
如：You needn't get up so early every day.你不必每天都起这么早。
She shouldn't speak to her mother in that way.她不应该用那种方式和妈妈说话。
More and more trees must be planted in China.在中国必须种植更多的树木。
Many of the stars can not be seen because they are far away from us.很多星星我们都看不到，因为它们离我们太远了。
1.“情态动词+动词原形”表示对现在的推测。
1can表示推测时一般用于否定句或疑问句。
如：That man can't be her husbandshe is still single.
Who is knocking at the door？Can it be the postman？
2must表示肯定的推测，一般用于肯定句中。
如：He must be in his office now.
Mr Li must be working now，for the lights in his office are still on.
3might表示推测时不一定是may的过去时，只是表示其可能性较小。
如：The man may be the headmaster.
—Where is Mr Li？
—He might be working in his office.
—May Mr Li come？
—He might not come here.
4Could表示推测时，语气can比要弱，说话者留有余地。
如：—Could it be an animal？
—It could not be，because it is not moving.
5Should表示推测的可能性比较大，仅比must的可能性 小一点。如：It is already 10 o'clock now they should be there.
2.情态动词表示对过去可能发生的动作或存在过的动作的推测性用法。
1“must +have done/been”表示“过去一定发生过某事或存在过某种状态”，不用于“musn’t+have”形式。
如：She must have seen the film before，hasn't she？注意反意疑问句的后半部分
You must have met uncle Wang in the shop yesterday，didn't you？ 注意反意疑问句的后半部分
2“should +have done /been”表示“本应当做某事，而实际上并没有做”；
“ shouldn't+完成式”表示“本来不应当做，而实际上却做了”。以上结构常带有说话者的责备的感情色彩。
如：You should have finished your homework earlier but in fact you did not finish it on time.
You shouldn't have gone to bed when you woke up at five but in fact you went to bed again then.
3“needn't+完成式”表示“本来没有必要做某事，而实际上却做了”。如：There was plenty of time.She needn't have hurried.
4“can't /couldn't+have done /been”表示“过去不可能发生了某事或存在过某种状态”。
如：I saw him just now.He can't have gone to Japan.
She said the man couldn't have stolen her car.
5“could+have done/been”表示“过去本来能够，可以做某事或成为某种状态，而实际上没有”，说话者有些遗憾。“could sb. have done /been-------？”是它的问句形式。
如：You could have stayed with the Smiths while you were in New York but in fact you stayed in a nearby hotel. Could Mr Li have helped this girl student？
6“may/might+完成式”表示“过去可能，本来可以于某事而实际上没有干”，might的可能性较小，语气较弱。
如：He may have finished reading the book.
She might have given you some help，however bus she was.
05
情态动词易混点归纳
易混点一：can和be able to
两者表示能力时用法相同，但can只有原形“can”和过去式“could”两种形式，在其他时态中 要用be able to 来表示。另外be able to 常常指经过努力，花费了时间和劳力之后才能做到某事。
Jim can't speak English.吉姆不会说英语。
He could speak English at 5. 他五岁时就会说英语。
We'll be able to see him next week.下星期我们将会见到他。
He has been able to drive. 他已经会开车了。
I'm sure you'll be able to finish it quickly.我相信你能迅速地完成。
We were able to reach the top of the mountain at noon.我们能在中午到达山顶。
易混点二：can和may
1.can 和 may 均可用来征求意见或许可，意为“可以”， 一般可互换使用。如：Can/ May I help you ？ 我能帮助你吗？
2.can 和may 表示可能性时的区别：
1在肯定句中用 might，may，must，不用can
2在疑问句中表示推测用can，不用 might，may，must
3在否定句中用can't（不可能）， 不用 may， must。如：She may be in the classroom . 她可能在教室里。Where can they be now？ 他们现在可能在哪儿？That can't be true. 那不可能是真的。
易混点三：may be 和maybe
may be的may为情态动词，be为动词原形，在句中作谓语；
maybe是副词，意思为大概、也许，相当于perhaps，用在句首，作状语。
例如：He may be wrong，but I’m not sure. 也许他错了，但我也不确定。
易混点四：can't 和 mustn't
1.can't 根据其基本用法可译为：
1不会。如：I can't speak English . 我不会说英语。
2不能。如：We can't do it now because it's too dark.天太黑了，我们现在干不了。
3否定句中表示推测。“不可能”，如：The man can't be our teacher because he is much younger than our teacher. 那个人不可能是咱们老师，他年轻得多。
2.mustn't 意为“ 禁止、不许”， 用来表达命令，表示强烈的语气。
You mustn't play football in the street. It’s too dangerous.
你不可以在街上踢足球，太危险了。
易混点五：must 和 have to
1.must 侧重于个人意志和主观上的必要。have to 侧重于客观上的必要，可用于现在时、过去时和将来时。
I know I must study hard.我知道我必须努力学习。
My brother was very ill， so I had to call the doctor in the mid-night.我弟弟病得厉害，我只得半夜里把医生请来。
I haven't got any money with me，so I'll have to borrow some from my friend.我身上没带钱，只好向朋友借点了。
He said they must work hard.他说他们必须努力工作。
2.have to可以用于多种时态；而must只用于一般现在或将来。
如：The composition is due to hand in this morning， so I had to finish it last night. 作文今天早晨到期，因此我不得不昨天晚上完成。
易混点六：used to do/be used to doing/be used to do…/be used for doing sth
used to do表示过去常常发生的动作，强调过去，只用于过去，注意用to do，不用doing形式；而be used to doing意为“习惯做…”，be可有各种时态；be used to do意为“……被使用去做……” 为被动语态形式；be used for doing sth“用作……” 。
如：My father used to eating meat.我父亲过去起床晚，但现在不得不早起了。
She is used to eating meat.她习惯吃肉。
He wasn't used to eating in a restaurant.他不习惯在饭店吃饭。
A knife can be used for cutting things.刀可以用来割东西 A knife can be used to cut things.刀可以用来割东西
06
情态动词例题解析
1.—________ you pass me a pen？ I'd like to write down the phone number.
—Sure. Here it is.
A. Can B. Need C. Might D. Must
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