若与过去事实相反，条件从句的谓语用过去完成时(had+过去分词)，主句谓语用“should (would, could, might)+have+过去分词”：

If I’d left sooner，I’d have been on time. 要是我早点动身，我就准时到了。(但我动身太迟了)

If we had found him earlier we could have saved his life. 要是我们当时早点找到他的话，我们就可以救活他。(可惜我们找到他太晚了)

若与现在事实相反，条件从句的谓语用过去式(be通常用were)，主句谓语用“should (would, could, might)+动词原形”：

If you took a taxi，you’d get there quicker. 如果你坐出租车去，你可以快一点到那里。(但你不坐)

If I knew her number I could ring her up. 要是我知道她的电话号码，我就可以给她打电话了。(可惜我不知道)

原则上说，if it weren’t [wasn’t] for 用于谈论现在的情况，而if it hadn’t been for 用于谈论过去的情况。但实际上if it weren’t [wasn’t] for有时也可用于谈论过去的情况：

If it weren’t for their help, we couldn’t have got over the difficulties. 要不是他们帮助，这些困难我们是克服不了的。

虚拟条件句的常见类型

快速搜索： 虚拟条件句的常见类型

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虚拟条件句的常见类型有三种，条件句有真实条件句和非真实(虚拟)条件句两种。真实条件句所表示的假设是有可能发生的，而非真实条件句则通常表示一种假想，与事实相反或不大可能会发生：

If I have time, I will go with them. 假若我有时间，我就同他们去。(陈述语气)

If I were you, I would go with them. 假若我是你，我就同他们去。(虚拟语气)

虚拟条件句的三种基本类型

这两个句型有时可用but for, without等替换。如：

要不是有你帮忙，我们是不会成功的。

If it hadn’t been for your assistance we wouldn’t have succeeded.

=But for your assistance we wouldn’t have succeeded.

=Without your assistance we wouldn’t have succeeded.

这两个句型是If it weren’t for…和If it hadn’t been for…，这是两个很常用的虚拟语气句型，也经常受到命题人的青睐，其意为“若不是(有)”“要不是有”。如：

If it weren’t for water, no plant could grow. 要是没有水植物就无法生长。

You wouldn’t be anywhere if it weren’t for Ruth. 若不是有鲁思你不会有任何成就。

If it hadn’t been for the doctor, he would have died. 要不是医生救了他，他就会死了。

If it hadn’t been for Mary, I might not have understood. 要不是有玛丽，我可能还不理解。

4. If he had seen you yesterday，he would haveasked you about it.

→Had he seen you yesterday，he would haveasked you about it.

他昨天要是看到了你，他就会问你这事了。

顺便说一句，以上移至句首的 had不一定是助动词，如果是实义动词也可倒装：

If he had money，he would buy a car.

→Had he money，he would buy a car.

他要是有钱，他就会买一辆小车。

巧顾课外辅导介绍两种常考的虚拟语气句型

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快速搜索： 虚拟语气句型

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巧顾课外辅导介绍两种常考的虚拟语气句型：If it weren’t for…和If it hadn’t been for…

3. If I could do it，I would.

→Could I do it，I would.

要是我能做此事，我一定会做。

2. If I were you，I would do it at once.

→Were I you，I would do it at once.

假若我是你，我就会马上做。

1. If he should fail，he would kill himself.

→Should he fail，he would kill himself.

万一失败，他就会自杀。

21. The guard said that he would not let him in if he had no pass.

→ The guard said,“I will not let you in if you have no pass.”

虚拟语气的倒装形式怎么用?

快速搜索： 虚拟语气的倒装形式怎么用 虚拟语气的倒装形式

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虚拟语气的倒装形式怎么用?请看典型考题：

__________ your address，I would have written to you.

A. Did I know B. Were I to know

C. Had I known D. If I should know

此题应选 C。这是虚拟语气的倒装形式。当虚拟条件句中含有 were，had，should，could等动词时，可以将if省略，然后将 were，had，should，could 等词移至句首：