1.we would had already failed without your help
2.we would prevented him if we know it in time
3.i should took care of you if i wasn't so busy last week
4.i was very busy last week,or i should looked after you
5.i will talk to him if i encounter him on occasion
6.you would done better if you were in my position
7.he hopes himself didn't make that so great mistake
——除5、7均为虚拟语气