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 …
在虚拟语气中，would have done经常以 两种结构出现。 1. I would have done……, but…… 我本想做……但由于一些原因，没有做成. 当然 …
had / would sooner / rather + that...从句中意为“宁愿”，用did（be动词用were）表示对现在或将来的虚拟；用had done表示对过去 …
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