大家好，日前和朋友讨论到一句用法，请各位不吝赐教：
I don’t know the reason for him doing this.
（我不知道他这么做的原因）
这句文法是正确的吗？如果改成
I don’t know the reason of him doing this.
呢？因为我想说”the reason of him”感觉可以当作类似所有格：his reason 的效果？
还是英文没有这种用法><？
我们已知这句如果要用
I don’t know his reason for doing this.
或是
I don’t know why he did this.
是可以的，那么第一、二句呢？
感谢各位！

是不是不用接介系词？然后应该在前面加疑问--＞ I don't know what the reason he did this也可能he前面可以加makes查了一下，reason 后面是接for，要用of的话必须用byreason of接why的话可以省略why

I don't know the reason why he did this.经询问过母语人士后得到的回答是：All of those sensors can be correct. They all said the same thing. Themost common way would be... I don’t know the reason he did this.更正*sentences* 对方打错字。