would加完成时表示什么

would have done
本应该做而未做

would not have done 本不应该做而做了

表虚拟语气
would have done 本应该……

是would have done对吧,will是一般将来时的标志,而would则是过去将来时的标志,have done意味着动作已经完成,也就是完成时的标志,那would have done则当然是过去将来完成时了!

过去将来完成时 虚拟语气 would have done
本应该做而未做

表示对以前事的一种看法:认为早就该做了,可就是没有做.
属于"虚拟语气",
If you had been there, you could have seen me.如果当时你在那儿的话,你就可以看到我的.(可惜的是你当时没有在那儿)