高三英語語法必背知識點
學習任何一門科目都離不開對的知識點,尤其是同學們在學習英語時,更要總結(jié)各個語法知識點,這樣也方便同學們?nèi)蘸蟮膹土?。下面小編為大家?guī)砀呷⒄Z語法必背知識點，希望對您有所幫助!
高三英語語法必背知識點
虛擬語氣在一些特殊詞中的使用或含蓄條件句
1.wish后的賓語從句。
與現(xiàn)在愿望不一致，用主語十過去時，例如：
I wi。hIwere you.
與過去愿望不一致，用主語+had+過去分詞，例如：Iwish I had visited the White House whenI was in the States與將來愿望不一致，用主語+would (could)+原形。
2.It's time句型：當lt's tine后用that從句時應該為主i吾+should+動詞原形或主語十過去時，例如：It，s time thatyou went to school.或It's time that you should go to schooL
3- If only引起的感嘆句相當于“How I wish+賓語從句”。
(l)If only he could come.他要能來就好了。
(2)If only I had known the answer.我要早知道答案就好了。
4.WOuld rather，as if(though)引導的從句也需使用虛擬語氣，表示過去的情況用過去完成時，表示現(xiàn)在與將來的情況用過去時，例如：
(l)I'd rather you posted the letter right away.
(2)She loves the children as if they were hers.
5.含蓄虛擬條件句含蓄條件句是指句中沒有明顯的虛擬條件句，而是利用其他手段來暗示存在虛擬條件。但是這類隱含式虛擬條件句往往都可以轉(zhuǎn)化為if引導的條件句。常用來表示含蓄虛擬條件的手段有：
(1)介詞或介詞短語。如but for，but that，without,in case of, under more favorable condition等。
(2)連詞。如so that, unless, in case, supposing,lest, provided(倘若……)，for fear that(唯恐)，in orderthat, on condition that, if only(要是……就好了)等。
注意：lest, for fear that和in case引起的從句中謂語動詞多用should+動詞原形，但也可以不用虛擬語氣，而用動詞的陳述語氣形式。例如：The foreign teacher spokeslowly in case we misunderstood him這位外籍教師說得很慢以免我們誤解。
(3)通過上下文及內(nèi)在含義，句中往往有but,otherwise, unfortunately等類似轉(zhuǎn)折詞。
without, but. but for, otherwise引起的短語或句子常暗含著含蓄條件。例如：
①Without you,1 would never know him
②But for your oooperation, we wouldn't have done it
③But that she was afraid, she would have said no. .
④i would be most glad to help you, butI am busy now.
⑤I would have come to the party yesterday, but ljwas working.
⑥I am busy now, otherwise l would do you the favor!
高三英語語法基礎知識點
一、不定式做主語：
1、不定式做主語一般表示具體的某次動作。動名詞doing表示習慣的，經(jīng)常的動作。
e.g:Tofinishthebuildinginamonthisdifficult.
Todosuchthingsisfoolish.
Toseeistobelieve.(對等)
注:1).不定式作主語時,謂語用單數(shù)
2).當主語較長，謂語較短時，常用it做形式主語，而將不定式放到謂語的后面。
it做形式主語，不定式放在謂語動詞之后常用于下列結(jié)構中：
(1)Itis/was+adj.+ofsb.todo…
(2)Itis+adj.+forsb.+todo…
Itiseasy/difficult/hard/foolish/unwise/right/wrong/unnecessary
(3)itis+a+名詞+todo...
Itisapity/apleasure/apleasantthing/one’sduty/anhonor/ashame/acrime/noeasyjob…todo
Ittakes(sb.)sometime/courage/patience…todo…
Itrequirescourage/patience/hardwork…todo…
注意:probable和possible均可作表語，但possible可以用不定式作真實主語，而probable不能用不定式作真實主語。
Itisprobableforhimtocometothemeeting.(錯)
Itispossibleforhimtocometothemeeting.
Itispossible/probablethathewillcometothemeeting.
高三英語語法重要知識點
用固定的情態(tài)動詞表示的虛擬語氣
1. should +動詞原形(有時省略should)
(1)用在動詞如advise, command, demand, desire, insist, order, propose, recommend, request, require, suggest, urge等后的賓語從句中。例如：
1)They requested that we (should) send a delegation to their country.
2)She urged that he write and accept the post.
(2)用在it is suggested, it is desired, it is required, it was ordered, it was proposed, it has been decided, it is necessary (essential, imperative, important, desirable) that等引出的主語從句中。例如：
1)It is desired that we (should) get everything ready by tonight.
2)It is necessary that the teacher (should) have a thorough knowledge of the subject he teaches.
(3)用在suggestion, motion, proposal, order, recommendation, plan, idea, requirement等引起的表語從句和同位語從句
例如：He put his coat over the child lest he should catch cold.