英语中的语气分为陈述语气、祈使语气、虚拟语气三类。虚拟语气用来表示假想，而不表示客观存在的事实，所说的是一个条件，不一定是事实，或与事实相反。虚拟语气通过谓语动词的特殊形式来表示，下面常州环球雅思为你介绍1. If sb had done sth (坏事)， sb would never have done sth (好事).
如果某人过去做了某事(坏事)，那么他永远不可能做某事。
If Hugh Miller， after toiling all day in quarry (采石场)， had devoted his evenings to rest and recreation， he would never have become a famous geologist.
2. Sb would never have done sth (好事1) ， never have done sth (好事2)， if sb had done sth (坏事)某人永远不可能做某事，永远不可能做某事，如果某人过去做了某件坏事。
The celebrated mathematician， Edmund Stone， would never have published amathematical dictionary， never have found the key to science of mathematics， if he had given his spare moments to idleness.
3. Had sb done sth(坏事) ，sb would never have done sth (好事)如果某人过去做了某件坏事，而不是去做某件好事，那么他永远不可能做某事(好事)。
Had the little Scotch lad， Ferguson， allowed the busy brain to go to sleep while he tended sheep on the hillside， instead of calculating the position of the stars by a string of beads， he would never have become a famous astronomer.