第一类 If虚拟条件句
分三种时态:与现在事实相反、与过去事实相反、与将来事实相反。
*条件句有真实条件句和非真实(虚拟)条件句两种。真实条件句的假设是有可能发生的,而非真实条件句的假想与事实相反或不大可能会发生,试比较:
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 had time, I would go with them. 假若我有时间,我就同他们去。(虚拟语气)
这是对现在事实的虚拟,事实是我没有时间,所以我没有和他们去
If条件句虚拟
时态类型 |
主句 |
If引导的从句 |
例句 |
与现在事实相反 |
would/should/could/might+ V原 |
动词过去式 did *be 多用were |
1. If I were you, I should study English. 2. I would certainly go if I had time. |
与过去事实相反 |
would/should/could/might + have done |
动词过去完成式 had done |
1. If you had taken my advice, you would not have failed in the test. 2. If I had left a little earlier, I would have caught the train. |
与将来事实相反 |
would/should/could/might + V原 |
①动词过去式 ②should +V原 ③were + to do |
1.If you came tomorrow, we would have the meeting. ① 2. If it were to rain tomorrow, the meeting would be put off.③ |
*规律总结:从句都往过去推一个时态,如:与现在相反的if从句就用过去时;与过去相反用过去完成时(即过去的过去) |
注:几点特别说明
1、l would/should/could/might 主句谓语中的should主要用于第一人称后;would表示结果还表示过去经常常常做某事,might表示可能性,could表示能力、允许或可能性。比较:
If you tried again ,you would succeed. 要是你再试一试,你就会成功的。(would表结果)
If you tried again, you might succeed. 要是你再试一试,你可能会成功的。(might表可能)
If you tried again ,you could succeed. 要是你再试一试,你就能成功了。(could表能力)
2、 错综时间虚拟条件句 即条件从句与主句所指时间不一致,如从句指过去,而主句即指的是现在或将来,此时应根据具体的语境情况,结合上面提到的三种基本类型对时态作相应的调整:
If it had rained last night, the ground would be wet now. 要是昨晚下过雨的话,现在地面就会是湿的。
You would be much better now if you had taken my advice. 假若你当时听我的话,你现在就会好多了。
3、 If虚拟条件句的否定(含蓄条件句) 常考两个句型:If it weren’t for…和If it hadn’t been for…,其意为“若不是(有)” “要不是”。如:
If it weren’t for water, no plant could grow. 要是没有水植物就无法生长。
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.
4、 If虚拟条件句的倒装形式,即把were, had, should置于句首。例:
Were I in school again (= If I were in school again), I would work harder.
Had you asked me, I would have told you. (=If you had asked me,…)