備考英語(yǔ)四六級(jí)的時(shí)候需要大量的積累單詞和掌握語(yǔ)法，很多同學(xué)認(rèn)為六級(jí)語(yǔ)法很難。下面是小編給大家整理的六級(jí)語(yǔ)法知識(shí)，大家可以作為學(xué)習(xí)的參考。

英語(yǔ)六級(jí)基礎(chǔ)語(yǔ)法知識(shí)：虛擬語(yǔ)氣

1. 表示現(xiàn)在/過(guò)去/將來(lái)情況的虛擬條件句

虛擬條件句主要有三種結(jié)構(gòu)：

1)　表示與現(xiàn)在情況相反：主句謂語(yǔ)用“would / could / might +動(dòng)詞原形”，從句謂語(yǔ)用“動(dòng)詞的一般過(guò)去時(shí)”(動(dòng)詞be的過(guò)去式一律用were)。

If I were you, I would not accept his offer.

If I had time, I would certainly go to the cinema with you.

2) 表示與過(guò)去情況相反：主句謂語(yǔ)用“would / could / might + have +過(guò)去分詞”，從句謂語(yǔ)用過(guò)去完成時(shí)。

If I had got up a little earlier, I wouldn’t have missed the train.

If I had been more careful, I might have passed that exam.

3) 表示與將來(lái)情況相反：主句謂語(yǔ)用“would / could / might +動(dòng)詞原形”，從句謂語(yǔ)用“were +動(dòng)詞不定式”或“should +動(dòng)詞原形”。

If I were to do the job, I would not be able to have enough time to study.

If it should rain tomorrow, I would not go out with you.

2. 虛擬條件句連接詞if的省略

如果虛擬條件句的從句中含有were, had, should, could等詞時(shí)，可以省略連接詞if，但這時(shí)必須把were, had, should, could等詞移到主語(yǔ)前面，形成倒裝。這種句型主要用于書(shū)面形式。

Were I to do the job, I would finish doing it within two weeks.

Had it not been for his help, we couldn’t have arrived there on time.

Should it rain tomorrow, I would stay at home.

3. wish后賓語(yǔ)從句中的謂語(yǔ)構(gòu)成

動(dòng)詞wish后的賓語(yǔ)從句表示未實(shí)現(xiàn)的或不可能實(shí)現(xiàn)的愿望，其賓語(yǔ)從句中的謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣，有以下三種構(gòu)成形式。

1) 表示現(xiàn)在不可能實(shí)現(xiàn)的愿望，賓語(yǔ)從句中的謂語(yǔ)動(dòng)詞用一般過(guò)去時(shí)。(be的過(guò)去式為were)。

I wish I had enough money to buy a car.

I wish I were as young and energetic as you.

2) 表示過(guò)去未能實(shí)現(xiàn)的愿望，賓語(yǔ)從句中的謂語(yǔ)動(dòng)詞用過(guò)去完成時(shí)(had +過(guò)去分詞)或“would / could + have +過(guò)去分詞 ”。

I wish I hadn’t made such a mistake.

I wish I could have done it better.

3) 表示將來(lái)不可能實(shí)現(xiàn)的愿望，賓語(yǔ)從句中的謂語(yǔ)動(dòng)詞用“would / should (could, might) +動(dòng)詞原形”。

I wish I would not get old.

I wish I could travel around the world one day.

4. 某些動(dòng)詞后的賓語(yǔ)從句中謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣

在一些動(dòng)詞后面的賓語(yǔ)從句中，謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣。這時(shí)，謂語(yǔ)動(dòng)詞用動(dòng)詞原形或should +動(dòng)詞原形。這類動(dòng)詞一般表示命令，要求，決定，建議，主張等概念，主要有：advise, ask, command, decide, demand, desire, direct, insist, move, order, propose, recommend, request, require, suggest,等。

The workers demanded that their wages (should) be raised by 10 per cent.

The teacher decided that you do the experiment first.

5. 某些名詞后的表語(yǔ)從句和同位語(yǔ)從句中謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣

在一些名詞后面的表語(yǔ)從句和同位語(yǔ)從句中，謂語(yǔ)動(dòng)詞要用虛擬語(yǔ)氣。這時(shí)，謂語(yǔ)動(dòng)詞用動(dòng)詞原形或should +動(dòng)詞原形。這類名詞一般表示命令，要求，決定，建議，主張等概念，主要有：advice, idea, instruction, motion, order, plan, proposal, recommendation, request, requirement, suggestion,等。

My suggestion is that we (should) send for a doctor immediately.

He gave the order that they (should) do the experiment again.

6. 錯(cuò)綜時(shí)間條件句

條件從句表示的動(dòng)作和主句表示的動(dòng)作，有時(shí)發(fā)生的時(shí)間是不一致的.如從句是對(duì)過(guò)去情況的假設(shè)，而主句可能是對(duì)現(xiàn)在正在進(jìn)行情況的假設(shè)。 這種句子稱為錯(cuò)綜時(shí)間條件句.

If the weather had been more favourable, the crops would be growing still better.

要想順利通過(guò)英語(yǔ)六級(jí)考試，在備考的時(shí)候要掌握學(xué)習(xí)方法，方法用對(duì)，學(xué)習(xí)才能提高效率。