英語四級語法訓(xùn)練：虛擬語氣

虛擬語氣
1. 表示現(xiàn)在/過去/將來情況的虛擬條件句
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：主句謂語用“would / could / might 動詞原形”，從句謂語用“動詞的一般過去時”(動詞be的過去式一律用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) 表示與過去情況相反：主句謂語用“would / could / might have 過去分詞”，從句謂語用過去完成時。
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) 表示與將來情況相反：主句謂語用“would / could / might 動詞原形”，從句謂語用“were 動詞不定式”或“should 動詞原形”。
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，可以省略連接詞if，但這時必須把were, had, should, could等詞移到主語前面，形成倒裝。這種句型主要用于書面形式。
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后賓語從句中的謂語構(gòu)成
動詞wish后的賓語從句表示未實(shí)現(xiàn)的或不可能實(shí)現(xiàn)的愿望，其賓語從句中的謂語動詞要用虛擬語氣，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，賓語從句中的謂語動詞用一般過去時。(be的過去式為were)。
I wish I had enough money to buy a car.
I wish I were as young and energetic as you.
2) 表示過去未能實(shí)現(xiàn)的愿望，賓語從句中的謂語動詞用過去完成時(had 過去分詞)或“would / could have 過去分詞 ”。
I wish I hadn’t made such a mistake.
I wish I could have done it better.
3) 表示將來不可能實(shí)現(xiàn)的愿望，賓語從句中的謂語動詞用“would / should (could, might) 動詞原形”。
I wish I would not get old.
I wish I could travel around the world one day.
4. 某些動詞后的賓語從句中謂語動詞要用虛擬語氣
在一些動詞后面的賓語從句中，謂語動詞要用虛擬語氣。這時，謂語動詞用動詞原形或should 動詞原形。這類動詞一般表示命令，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. 某些名詞后的表語從句和同位語從句中謂語動詞要用虛擬語氣
在一些名詞后面的表語從句和同位語從句中，謂語動詞要用虛擬語氣。這時，謂語動詞用動詞原形或should 動詞原形。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. 錯綜時間條件句
條件從句表示的動作和主句表示的動作，有時發(fā)生的時間是不一致的.如從句是對過去情況的假設(shè)，而主句可能是對現(xiàn)在正在進(jìn)行情況的假設(shè)。 這種句子稱為錯綜時間條件句.
If the weather had been more favourable, the crops would be growing still better.

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