想要學好英語四級怎麼能不知道情態動詞的用法呢?下面就讓小編為大家詳解一下吧。
1)用於第一人稱徵求對方的意見，如：
What shall I wear on the journey? 我路上穿什麼好呢?
Shall we dance? 我們跳舞好嗎?
2)shall 用於第二、三人稱時表允諾，警告，命令，威脅(現已少見)，如：
She shall get her share. 她可以得到她的一份。
You shall have it back tomorrow.你明天可以將它拿回。
情態動詞should一般不應被認為是情態動詞shall的過去式，主要用法有：
1)用於第一人稱疑問句中詢問對方的意願，但語氣較委婉溫和，如：
What should we do now? 我們現在該怎麼辦?
2)表示應該、必須，常與must 換用。例如：
We should (must) master a foreign language at least.
我們應當至少掌握一門外語。
3)"should+be+表語"的`結構，表示推測或驚奇。例如：
They should be back by now. 他們現在應該回來了吧。
I am sorry that she should be so careless. 我感到遺憾她竟會那樣粗心。
4)"should+have+過去分詞"的結構，表示過去該做而實際上尚未做的動作或行為;其否定則表示發生了不應該發生的行為。其同義結構"ought to have +過去分詞",表示過去"早應該"、"本當"之意，語氣較強。例如：
I should have thought of that. 這一點我是應當想到的。(但沒想到)
They should not have left so soon.他們不應當走得這麼早。(但已走了)
5) 在"It is natural (strange, natural, necessary, surprised, impossible, important ) that......"句型中，主語從句中的謂語動詞要用should +動詞原形"表示"理所當然"、"奇怪"、"必要"、"驚異"等的意思。在lest(以免)、for fear (that) (以防)、in case(以備萬一)等之後也要用should+動詞原形;在advise, sugest, order, demand, request 等的從句中should+do"例如：
It is necessary that he(should) be sent there at once.
有必要馬上派他到那裡去。
It is strange that he should say so. 他會說這樣的話真是奇怪。
Let us go at once lest we should be late for the train.
我們馬上走吧，以免趕不上火車。
will和would的用法
1)表示意志，決心或願望。例如：
Surely we will support all the people in the world in their struggle for peace.
我們一定要支援全世界人民爭取和平的鬥爭。
He would not let me try it . 他不肯讓我去試。
2)will表示經常性、習慣性、傾向性，would表示過去的習慣行為。
He will sit there hour after hour looking at the traffic go by.
他會經常一連幾個小時坐在那兒觀看來往的車輛。
He would come to see me when he was in Beijing.
他在北京時，常來看望我。
3)用於第二人稱作主語的疑問句中，表示對對方的請求，would的語氣比will委碗
Would/will you kindly tell me the way to the station? 請問到火車站怎麼走?
4)表可能性
This will be the book you are looking for.
這可能就是你要找的書。
She eould be about 60 when she died.
他死時大概60歲。
need和dare的用法
情態動詞need 實義動詞 need
句型 時態 動詞
情態動詞dare 實義動詞 dare
肯定句 現在時 dare to 少用 dare/dares to do
過去時 dare to 少用 dared to do
否定句 現在時 daren't/dare not do do/does not dare (to) do
過去時 dared not do did not dare (to) do
疑問句 現在時 Dare he do? Do you/Does he dear (to) do?
過去時 Dared he do? Did he dare (to) do
needn't have v-ed 表示過去做了某事，但沒有做的必要， 意為"本沒必要..."。例如：
You needn't have waken me up; I don't have to go to work today
表推測的情態動詞句子的反意疑問句
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?
：情態動詞+行為動詞進行式
情態動詞+行為動詞進行式(即情態動詞+ be + v-ing形式)，表示推測或評論某動作現在是否正在進行。例如：
1)He must be playing basketball in the room.
2)She may be staying at home.
情態動詞+行為動詞完成進行式
情態動詞+行為動詞完成進行式(即情態動詞+ have been + v-ing 形式)，表示推測或評論過去某動作是否正在進行或一直在進行。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意為"過去常常"，"過去一直";be used to +v-ing / n(名詞)意為"習慣於";be used to +v意為"被用來(做某事)"。
(2)used to只表示過去，而be used to +v-ing / n可表示現在、過去或將來。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.
用作情態動詞的其他短語
would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情態動詞。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：這些短語後一般直接跟動詞原形d (had) rather, would (had) sooner, would (just) as soon後可跟that 引導的從句，that 常省去，從句要用虛擬語氣。對現在和將來的假設用過去時，對過去的假設用過去完成時。例如：
1)I would rather you came on Sunday.
2)I would sooner you hadn't asked me to speak yesterday.
