新概念英语第三册语法辅导：虚拟语气1

英语自学网

　　虚拟语气用来表达不可能或难以实现的愿望，与事实相反的假设，通常分为基本的三种形式。
        　　1. 与现在事实相反的虚拟：
        　　If + did / were + ..., ... would/ should/ could/ might + do （动词原形）
        　　If I were you, I would go abroad at once. (I am not you.)
        　　If he knew it now, he could help me. (He doesn't know it now.)
        　　2. 与过去事实相反的虚拟：
        　　If + had done + ..., ... would (might) have done ...
        　　If I had known your telephone number yesterday, I would have phoned you. (I didn't know your telephone number.)
        　　If you had come here a little earlier just now, you might have met her. (You didn't come here earlier.)
        　　3. 与将来事实相反的虚拟：
        　　(1) If + should + v., ... would + v. （可能性很小）（译作“万一”）
        　　If it should rain tomorrow, you could stay at home.
        　　If I should fail, what should Ido?
        　　(2) If + did / were to + v ..., would + v. （完全不可能）
        　　If the sun were to rise in the west, I would lend you the money.
        　　If you finished it in 3 minutes, I would give you my car.