最近重新学习情态动词，有两点发现，一是新鲜，二是局限。
在看电影、电视剧的过程中，听演讲的过程中，以及在平时与英国人交流的过程中，有一个特别的发现，那就是情态动词使用的频率相当之高。其实，把情态动词准确掌握并非易事。因为就那么几个单词，可是用法却五花八门，一不小心就会载个跟头。语法的学习从来都不是件趣事，需要的就是理解、记住并使用。曾经学过的那些枯燥乏味的语法条文，可以是生活中常见、常用、常听到的十分接地气的、实用的、地道的表达。
比如：will和would
In a speech, we can stress will or would to criticize people’s characteristic behavior or habits:
例句：Shewill leave all the lights on in the house when she goes out.
I was happy when Sam left. He would talk about people behind their backs.
When we use stressed would in this way,we can also use it to talk about a particular occasion in the past. We suggest that what happened was predictable because it was typical of a person’s behaviour.
例句：
A: Jack’ say he can’t help because he’s got a lot of work on.
B: Well, he would say that – he always uses that excuse.
May, might, can和could:表示可能性possibility
We can use can in affirmative sentences when we talk about a more general possibility of something happening rather than the possibility of something happening in a particular situation:
例句：
The temperaturecan sometimes reach 35 in July.
Mountain daisescan be yellow or red.
We prefer may rather than can in more formal contexts.
例句：Exceeding the stated dose may cause drowsiness.
We don’t use may to to ask questions about the possibility of something happening. Instead we use, for example,could (n’t)or the phrase be likely:
Could it be that you don’t want to leave?
Are you likely tobe visiting Greece again this summer?
It is possible touse might in this type of question, but it is rather formal.
例句：Might they be persuaded to change theirminds?
否定如何表达：
There can’t/couldn’tbe any milk left – I would have seen it in the fridge.
There can/couldhardly be any doubt that he was guilty.
We use may not ormight not to say that it is possible that something is not true, and can’t orcouldn’t to say that it is not possible that something is true.
May, might, can和could:表示可能性possibility
During the war,the police might arrest you for criticising the king.
We use might (not’may’) + infinitive to talk about what was typically the case in the past.
We use may/might + be + -ingto say itis possible that something is happening now or to talk about a possible futurearrangement.
例句：
He isn’t in his office. He may/might be working athome today.
When I go to Vienna I may/might be staying withRichard, but I’m not sure yet.
Couldcan be usedin the same patterns instead ofmay
or might, particularly when we want to show that we are unsure aboutthe possibility.
David didn’t know where the ball was, but he thought his sister might have been playing with it.
Can, could和be able to：ability
表示对未来的决定：用can
You can go homewhen you’ve finished writing your report.
Perhaps we canmeet next Friday.
If the idea want to express needs a to-infinitive, an -ing form, or a perfect tense, or if itfollows another model verb, we use be
able to, not can or could.
例句：
It was awful,not
being able tosee you for so long.
Since he left, none of other team members have been able tomatch hisenthusiasm.
We don’t use be able to:
（1）When we talk about something that is happening as weare speaking.
例句：Look, I canswim.
（2）Before be + past participle:
例句：This furniturecan be assembled by any one, with just a screwdriver.
must和have (got) to
We prefer have(got) to when we talk about a necessity that is characteristic of a person.
Ann has got to have at least eight hours’ sleep anight.
She has to drink two cups of coffee in the morningbefore she feels really awake.
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