We could nothave been more disappointed about them when we used.
第一部分表达“可能性”
一、现在的可能性
通常情况下，使用can表示可能性。
例如：Healthinsurance can be very expensive. (=It is sometimes expensive.)
在学术英语和科技英语中，我们常用may。
Over-prescribingof antibiotics may lead to the rapid development of resistant strains.
常用may，might和could表示特定的可能性：
This rashmay/might/could be a symptom of something more serious.
如何就可能性进行提问？
一般用Do you think发起。
Do you thinkthe shops might be open today?
我们也可以用may well,
might well和could well表达较大的可能性。
Don’t worry,the payment could well be in the post.
基于特定条件的可能性如何表达？
使用could或者might。
She couldlearn much more quickly if she paid attention.
如何表达“可能不”？
might not或者may not
The shop maynot be open today; it’s a public holiday.
如果确信某事“确定不…….”，使用can’t。
You reallycan’t drive to Oxford in under an hour.
二、将来的可能性
1. 使用will/won’t be to able to 表示肯定和否定的可能性。
We’ll beable to get a coffee at the theatre but we won’t be able to eat until after theshow.
2. 使用may, might或could谈论未来的动作不是很确定
Thedirectors may call a stockholders’ meeting
3. could谈论比may和might更小的可能性
You neverknow, she could find a perfect jot tomorrow. (It’s possible, but unlikely)
注意：不能用could not或者couldn’t表达现在或将来非常不可能的事
有时，使用may/might+have+past
participle谈论将来某一时间节点可能完成的动作
例如：Call me nextThursday; I might have finished the project by then.
三、过去的可能性
could一般表示过去的可能性（有时发生）
Teacherscould be very strict at my old school. (=sometimes they were strict)
学术英语：
同样的情况，在学术英语和科技英语中，使用might。
WealthyVictorian families might employ as many as a dozen indoor servants.
使用could/might+have+past
participle表示过去特定的可能性
She mighthave done it; she had the opportunity and the motive.
使用might have表示过去的机会，但是没有抓住。
I might havegone to drama school, but I chose history instead. (I had the opportunity but Idid’t go)
第二部分 表达“推测”
一、对现在的推测
1、如果有证据使我们强烈相信，使用must或have to
This mustbe the place – it’s the only bookstore in the street.
如果我们想强调，则使用have (got) to
You havegot to be joking! That was not a foul!
There hasto be some mistake. I didn’t order this furniture.
如果坚信不是真的，或者不可能，使用can’t或couldn’t
Hecan’t/couldn’t be he senior doctor, he’s far too young. (=I’m certain he isn’t)
She can’tbe working at the moment – I see her in the garden every morning.
注意：在这种情况下，不能使用mustn’t
我们可以使用can和could在wh-的问题中，或者带有only或hardly的句子中
Who canthat be at this time of night?
It canhardly be the postman. He only comes in the morning.
It canonly be Jack. He’s the only one with a key. (=I’m sure it is Jack)
使用might在tentative (less direct)的问题中：
Might thelosses be due to currently fluctuations?
在非正式英语中，增加well表示推测程度可能性的增大。
Let’scall the hospital. There may well be some news now.
使用couldn’t表示无法想象，因为不愿意做。
Icouldn’t pick up spider; they terrify me.
二、对现在和将来的期待
should/shouldn’t或ought
to/ought not to表示期待——期待现在或现在发生，因为我们已有的知识或者当前的情况。
The planetook off on time so it should be landing about now and there shouldn’t be anydelays.
注意：几乎不用should表示对消极情况或者不愉快情况（unpleasant）的predict。使用will。
There’llbe problems with traffic at that time. The roads will be awful.
三、对过去的推测
注意：
常用can’t+have或者couldn’t + have表达惊讶或不相信
Shecouldn’t have done it; she’s such a nice woman.
You can’thave been waiting for long – I only went out five minutes ago!
第三部分 责任和必要
一、现在和将来的责任
don’t
have to和don’t need to表示没有责任
You don’thave to pay to visit most museums in the UK.
must常用情况：
在书面说明中，经常使用被动。
Theelectricity must always be switched off before repairs are attempted.
must，should表示将来的责任
won’t
have to , won’t need to或者needn’t表示将来没有责任。
二、现在和将来的必要
need to，must和have to表示必要性，但不是命令、规则和法律，或表示非常重要的事。
Allliving beings need to take in sustenance in order to live.
Allliving beings must take in sustenance in order to live.
Allliving beings have to take in sustenance in order to live.
I reallyneed to be going now. I’m meeting Jack in half an hour.
We’llneed to set up a more intensive training regime.
如果表达必要性，但不表示谁应该做，使用need + -ing的形式。
That poorbird – his cage really needs cleaning.
使用don’t need to或者needn’t表达说话者感觉没有责任。
Weneedn’t put the heating on yet; it’s not cold enough.
三、过去的责任和必要
一般使用had to
使用should have done表示过去未完成的责任
注意：不用must表示责任
Therecord was finally released 18 months later than it should have been.
是哦有那个didn’t have to或didn’t need to表示过去没有责任
注意：need两种形式的差别
We didn’tneed to take warm sweaters, as the weather was so good.
(We don’tknow if the speaker took warm sweaters or not)
Weneedn’t have taken warm sweaters. We could have used the space in our luggagefor more books!
四、其他形式表示职责
be to来自某人或权威机构的命令
be
supposed to表lesser obligation，经常被忽略
be liable
to经常用于法律条文
be
required to用时正式文体
第四部分禁止和批评
一、现在和将来的禁止
使用must not (常mustn’t)
来自外来权威的禁止:
can’t/aren’tallowed to
isprohibited/forbidden
it isprohibited/forbidden to
may notuse: Hotel guests may not use the poll after 11 pm.
将来: won’t be allowed to或者can’t 表示对将来禁止
二、过去的禁止和批评
couldn’t或wasn’t
allowed对过去的禁止
注意：不使用must 表批评。
用might/could have done表示较弱的批评
You might have told me aboutthe party!
第五部分确定、习惯和意愿
1、现在和将来的确定
我们相信某事是确定的，但不知道是不是事实，用will或者won’t.
He’s coming. He’ll be on hisway now.
I hope she’s taken somewinter clothes because it won’t be warm at this time of year.
对于正在发生的事情，使用will/won’t + be + -ing的形式
He knows his succeor will behaving a hard time in his job.
如果知道某事为事实，比如有独立的证据，我们使用一般现在时态，正在发生的事情则使用现在进行时态。
He’s in Moscow. He called mefrom his hotel.
另外一种情况：
Sometimes we wish to make a
predication about the futre that someone made in the past.使用would/woudn’t。
We had to hurry to get him tothe hospital. It would be too late otherwise.
2.过去的确定
To refer to sth which we feelcertain has happened (but do not acturally knwo), we use:
will have pp.
We sent the invitation onMonday, so they will have received it by now.
similar: must have pp
使用won’t have pp to refer to sthwe feel certain has not happened
We sent the invitation onMonday, so they won’t have received it by now.
不用Mustn’t，但可以用can’t
We sent the invitations bysencond-class post. They can’t have received them yet.
三、现在的习惯和routine
will或won’t，表示习惯和routine，且可预测。
Every lessen is the same:he’ll sit down, get his books out and then he’ll start giving us instructions.He won’t greet us.
注意：we can extend this use ofwill to talk about attitudes and charactersitics.
The public will always sidewith the nurses in any dispute.
Thedominant male in this species will not tolerate the presence of other males.
但如果陈述简单事实，则使用一般现在时态。
可以使用will或一般现在时态，谈论aspects of capacity orability.
Thehall will hold 10,000 people.
说话中，使用will描述an annoying habit或批评。
We enjoy going out with them, but they will arguein public!
注意：we do not contract will when we use it in thisway – we stress it.
He will leave the lights on when he’s last out ofthe office!
使用will/won’t谈论非生命物体。
Whatever I do, my car won’t start first time oncold mornings.
四、过去的习惯和routines.
would/wouldn’t表示
在说话时，我们强调would/wouldn’t表示批评或谈论an annoying habit。
would/wouldn’t谈论非生命物体。
五、现在和将来的意愿
使用will表示我们同意做的事，表示愿意做。
He will act as referee today since Jack can’tmake it.
will或won’t在if引导的first conditional表示礼貌的要求。
If you’ll take a seat for a moment, he will bewith you soon.
使用won’t/shan’t表示拒绝
His secretary won’t book my flights. She says itisn’t in her job description.
六、过去的意愿
使用would/wouldn’t表示过去的意愿或拒绝。
Dad would always help us with our maths homework.
注意：不使用would表示某个特定场合的意愿，但是可以使用would not表示对某一特定场合的拒绝。
The tour guide was very helpful. Shecontacted/offered to contact/was willing to contact the Consulate for me when Ilost my passport.
The shop assistant wouldn’t change this jumperfor me, even though I hadn’t worn it.
第六部分其他的情态动词
一、允许
过去的允许，通常用could/couldn’t
In the 1950sBritish children could leave school at the age of fourteen.
二、建议
