2016英语四级语法情态动词解析
想要学好英语四级怎么能不知道情态动词的用法呢?下面就让小编为大家详解一下吧。
1)用于第一人称征求对方的意见，如：
What shall I wear on the journey? 我路上穿什么好呢?
Shall we dance? 我们跳舞好吗?
2)shall 用于第二、三人称时表允诺，警告，命令，威胁(现已少见)，如：
She shall get her share. 她可以得到她的一份。
You shall have it back tomorrow.你明天可以将它拿回。
情态动词should一般不应被认为是情态动词shall的过去式，主要用法有：
1)用于第一人称疑问句中询问对方的意愿，但语气较委婉温和，如：
What should we do now? 我们现在该怎么办?
2)表示应该、必须，常与must 换用。例如：
We should (must) master a foreign language at least.
我们应当至少掌握一门外语。
3)"should+be+表语"的`结构，表示推测或惊奇。例如：
They should be back by now. 他们现在应该回来了吧。
I am sorry that she should be so careless. 我感到遗憾她竟会那样粗心。
4)"should+have+过去分词"的结构，表示过去该做而实际上尚未做的动作或行为;其否定则表示发生了不应该发生的行为。其同义结构"ought to have +过去分词",表示过去"早应该"、"本当"之意，语气较强。例如：
I should have thought of that. 这一点我是应当想到的。(但没想到)
They should not have left so soon.他们不应当走得这么早。(但已走了)
5) 在"It is natural (strange, natural, necessary, surprised, impossible, important ) that......"句型中，主语从句中的谓语动词要用should +动词原形"表示"理所当然"、"奇怪"、"必要"、"惊异"等的意思。在lest(以免)、for fear (that) (以防)、in case(以备万一)等之后也要用should+动词原形;在advise, sugest, order, demand, request 等的从句中should+do"例如：
It is necessary that he(should) be sent there at once.
有必要马上派他到那里去。
It is strange that he should say so. 他会说这样的话真是奇怪。
Let us go at once lest we should be late for the train.
我们马上走吧，以免赶不上火车。
will和would的用法
1)表示意志，决心或愿望。例如：
Surely we will support all the people in the world in their struggle for peace.
我们一定要支持全世界人民争取和平的斗争。
He would not let me try it . 他不肯让我去试。
2)will表示经常性、习惯性、倾向性，would表示过去的习惯行为。
He will sit there hour after hour looking at the traffic go by.
他会经常一连几个小时坐在那儿观看来往的车辆。
He would come to see me when he was in Beijing.
他在北京时，常来看望我。
3)用于第二人称作主语的疑问句中，表示对对方的请求，would的语气比will委碗
Would/will you kindly tell me the way to the station? 请问到火车站怎么走?
4)表可能性
This will be the book you are looking for.
这可能就是你要找的书。
She eould be about 60 when she died.
他死时大概60岁。
need和dare的用法
情态动词need 实义动词 need
句型 时态 动词
情态动词dare 实义动词 dare
肯定句 现在时 dare to 少用 dare/dares to do
过去时 dare to 少用 dared to do
否定句 现在时 daren't/dare not do do/does not dare (to) do
过去时 dared not do did not dare (to) do
疑问句 现在时 Dare he do? Do you/Does he dear (to) do?
过去时 Dared he do? Did he dare (to) do
needn't have v-ed 表示过去做了某事，但没有做的必要， 意为"本没必要..."。例如：
You needn't have waken me up; I don't have to go to work today
表推测的情态动词句子的反意疑问句
He must/may be in the room, isn't he?
He can't be in the room, is he?
He must have finished the work, hasn't he?
He may have done the work last night, didn't he?
：情态动词+行为动词进行式
情态动词+行为动词进行式(即情态动词+ be + v-ing形式)，表示推测或评论某动作现在是否正在进行。例如：
1)He must be playing basketball in the room.
2)She may be staying at home.
情态动词+行为动词完成进行式
情态动词+行为动词完成进行式(即情态动词+ have been + v-ing 形式)，表示推测或评论过去某动作是否正在进行或一直在进行。例如：
1)They should have been meeting to discuss the problem.
2)He may / might have been buying stamps in the post office when you saw him.
used to +v, be used to +v-ing和be used to +v
(1)used to +v意为"过去常常"，"过去一直";be used to +v-ing / n(名词)意为"习惯于";be used to +v意为"被用来(做某事)"。
(2)used to只表示过去，而be used to +v-ing / n可表示现在、过去或将来。例如：
1)He used to smoke. Now he doesn't.
2)He's quite used to hard work / working hard.
3)The knife is used to cut bread.
用作情态动词的其他短语
would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情态动词。例如：
1)The soldier would sooner die than surrender.
2)The brave soldier would as soon die as yield to such an enemy.
3)I'd rather walk than take a bus.
4)If you don't like to swim, you may just as well stay at home.
注：这些短语后一般直接跟动词原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句，that 常省去，从句要用虚拟语气。对现在和将来的假设用过去时，对过去的假设用过去完成时。例如：
1)I would rather you came on Sunday.
2)I would sooner you hadn't asked me to speak yesterday.