虚拟语气主要有与现在事实相反、与过去事实相反、与将来事实相反的虚拟，以及几种特殊情况，should、wish等虚拟语气。
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 e here a little earlier just now, you might have met her. (You didn't e 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 I do?
(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.
