1.But for/without +n. ——would do虚拟现在/事实 would have done过去
2.Were it not for+n.——would do现在
Had it not been for+n.——would have done过去
3.Under more favourite condition.——would have done过去
4.comparative degree——would do/would have done
5.participle phrase——would do/would have done
6.would do ——present~
虚拟subjunctive , but——真实inductive
would have done——past
7.present —— would
in dicative真实 otherwise/or subjunctive虚拟
past—— would have done
8.Vmodal情态动词+have done
can't have done对过去否定的推测
must have done对过去肯定的推测
9.Be S.__or__⥤whether S. be__or__
10.If only/suppose/supposing
→were/did
→had done
