you_such a serious mistake if you had followed his advicemay not make might not have made 为什么b对？give me a chance

you_such a serious mistake if you had followed his advice
may not make might not have made 为什么b对？give me a chance

wouldn't have made
所述与过去的事实相反时,if从句的谓语形式用过去完成时:had done.即上文的"had followed".然后主句的谓语形式用would/could/should/might+have done.即我给的"wouldn't have made"
其实would/could/should/might都可以
我只是给了其中一个而已.