I'm sorry (that) what I did .能不能写成 I 'm sorry for (that) what I did?

I'm sorry (that) what I did .能不能写成 I 'm sorry for (that) what I did?

不能的.what是一个介宾短语,跟在for后面,插入that 之后某明奇妙地多了一个成分.

完全可以
I'm sorry (that) what I did 这个口语可以 书面尽量不要用

可以的！

I am sorry for what I did
I'm sorry (that) what I did是错误的!