Question

for your help,i really don't know what i would have done得前面应

Answer 1

Had it not been for your help,综合了两种语法现象：

1 虚拟语态,中文意思：如果没有你的帮助 （其实对方已经帮助他了,所以是虚拟语态）had done是表示的虚拟语态.

2.独立主格成分倒置,Had it not been,HAD 动词前置

希望能够帮到你!