2024年12月大学习英语四级基础语法备考

2024年12月大学习英语四级基础语法备考

虚拟语气

1. 表示目前/过去/以后状况的虚拟条件句

虚拟条件句主要有三种结构：

1)表示与目前状况相反：主句谓语用“would / could / might +动词原形”，从句谓语用“动词的一般过去时”。

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

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

2) 表示与过去状况相反：主句谓语用“would / could / might + have +过去分词”，从句谓语用过去完成时。

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) 表示与以后状况相反：主句谓语用“would / could / might +动词原形”，从句谓语用“were +动词不定式”或“should +动词原形”。

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. 虚拟条件句连接词if的省略

假如虚拟条件句的从句中含有were, had, should, could等词时，可以省略连接词if，但这个时候需要把were, had, should, could等词移到主语前面，形成倒装。这种句型主要用于书面形式。

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后宾语从句中的谓语构成

动词wish后的宾语从句表示未达成的或不可能达成的愿望，其宾语从句中的谓语动词要用虚拟语气，有以下三种构成形式。

1) 表示目前不可能达成的愿望，宾语从句中的谓语动词用一般过去时。。

I wish I had enough money to buy a car.

I wish I were as young and energetic as you.

2) 表示过去未能达成的愿望，宾语从句中的谓语动词用过去完成时或“would / could + have +过去分词 ”。

I wish I hadn’t made such a mistake.

I wish I could have done it better.

3) 表示以后不可能达成的愿望，宾语从句中的谓语动词用“would / should +动词原形”。

I wish I would not get old.

I wish I could travel around the world one day.

4. 某些动词后的宾语从句中谓语动词要用虚拟语气

在一些动词后面的宾语从句中，谓语动词要用虚拟语气。这个时候，谓语动词用动词原形或should +动词原形。这种动词一般表示命令，需要，决定，建议，倡导等定义，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 be raised by 10 per cent.

The teacher decided that you do the experiment first.

5. 某些名词后的表语从句和同位语从句中谓语动词要用虚拟语气

在一些名词后面的表语从句和同位语从句中，谓语动词要用虚拟语气。这个时候，谓语动词用动词原形或should +动词原形。这种名词一般表示命令，需要，决定，建议，倡导等定义，主要有：advice, idea, instruction, motion, order, plan, proposal, recommendation, request, requirement, suggestion,等。

My suggestion is that we send for a doctor immediately.

He gave the order that they do the experiment again.

6. 错综时间条件句

条件从句表示的动作和主句表示的动作，有时发生的时间是不同的.如从句是对过去状况的假设，而主句可能是对目前正在进行状况的假设。 这种句子称为错综时间条件句.

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

7. 某些主语从句中的谓语动词要用虚拟语气

某些表示命令，需要，决定，建议，倡导与“重要程度”和“紧迫性”等定义的主语从句中谓语动词要用虚拟语气。这个时候，谓语动词用动词原形或should +动词原形。这种主语从句一般由 “It is + 形容词/过去分词 + that引导的从句”构成。该结构中，常见的形容词主要有：advisable, appropriate, desirable, essential, imperative, important, necessary, obligatory, proper, urgent, vital等;常见的过去分词主要有：arranged, decided, demanded, desired, ordered, proposed, recommended, requested, suggested等。

It is necessary that you sTOP smoking so heavily.

It is arranged that you enter for this competition.

8. as if / though引起的从句

当as if / though引起的从句所表达的内容完全与实质状况相反或者纯粹是一种假设时，一般要用虚拟语气。假如从句表示与目前的事实相反，谓语动词用一般过去时;假如从句表示与过去的事实相反，谓语动词用过去完成时;假如从句表示与以后的事实相反，谓语动词用would + 动词原形;

They talked as if they had been friends for years.

I remember the whole thing as if it happened yesterday.

It looks as if it might rain.

Note: 假如as if / though引起的从句所表达的内容被看作是事实或者大概是真实的，则要用陈述语气。

It seems as if it is going to rain.

The meat tastes as if it has already gone bad.

9. lest, for fear that和 in case引起的从句

当lest, for fear that和 in case表示“以免，以防，生怕，惟恐”等时，在它们引起的从句中，谓语动词常用should + 动词原形。

He ran away lest he should be seen.

He’s working hard for fear that he should fall behind.

He left early in case he should miss the last train.

10. If only引出的从句

If only引出的从句用以表达感叹性的愿望，常译为“如果…就好了”。If only从句常常省略结果主句，且主要用在虚拟语气中，即从句的谓语动词用一般过去时表示目前或以后不可能达成的愿望，或用过去完成时表示过去没达成的愿望。

If only the rain would sTOP.

If only I’d listened to my parents.

Note: if only引出的句子偶尔也可用陈述语气，但考生需小心的是，在各类测试中一般都以用虚拟语气为正确答案。

11. would rather引出的从句

would rather意为“宁可”，接从句时常省略关系代词that。would rather后的从句要用虚拟语气，即从句谓语动词用一般过去时表示目前或以后的愿望，用过去完成时表示与过去事实相反的愿望。

I’d rather you told me the truth.

I would rather you came tomorrow than today.

I’d rather you hadn’t told me about it.

12. It is time 句型

该句型表示“该做…”，其后的定语从句中的谓语动词要用虚拟语气表示。在测试中从句的谓语动词用一般过去时。

It is time that we went to bed.

It is high time that somebody taught you to behave yourself.

13. 表示猜测的几种不一样的办法及意义

一些情态动词与动词的完成式连用可以表示对过去状况的猜测或者未达成的可能性。

1) could have + 过去分词

A. 表示对过去可能发生的事情的推断，意为，“可能做了某事”。

He couldn’t have seen her yesterday.

They could have lost their way.

B. 表示某事在过去本大概发生，但事实上并未发生，意为，“本可以做某事”。

We could have started a little earlier.

I could have killed her. It was a narrow escape.

2) may have + 过去分词

A. 表示对过去状况的推断，意为，“可能已做某事”。

He may have heard the news.

I might have come to a wrong conclusion.

B. 表示一种未达成的可能性，即本可以做某事，而事实上并没做，有时含有抱怨的口吻。

It was a narrow escape. You might have killed yourself.

A lot of men died who might have been saved.

3) must have + 过去分词

表示逻辑上的势必性，即根据某些现象判断过去一定发生过的某事。

She must have made a big mistake.

The city at one time must have been prosperous, for it enjoyed a high level of civilization.

4) needn’t have + 过去分词

表示过去不必做某事，但已经做了，即本可不必做某事。

You needn’t have woken me up. I don’t have to go to work today.

He needn’t have watered the flowers, for it is going to rain.

5) should / ought to have + 过去分词

表示过去应该做某事而事实上没做。

You should / ought to have done what your parents told you.

You should / ought to have been more careful.

6) shouldn’t / oughtn’t to have + 过去分词

表示过去不应该做某事而事实上却做了。

You shouldn’t / oughtn’t to have crossed the road when the lights were red.

They shouldn’t / oughtn’t to have left so soon.

7) would have + 过去分词

表示对目前或以后某时之前业已完成的动作的推断。可译为，“可能”、“或许”、“想来”。

He would have arrived by now.

She would have recovered by then.