不定式作but/except的宾语时候时候+TO 什么时候不加TO

I could/ can do nothing but/except + do sth.
When you find " do " in the main verb, you use" ...do sth without "to..." after but/ except.
I have no choice but/ except + to do sth.
There's no choice/ alternative but/except + to do sth.
Where you don't see or use " do/ does/ did" in the main verb, you use " to do..." after but/ except. As in the above two example sentence, you just find "have...or is..." in the main verb, don't you?
That's it.

前面有do的各种形式的时候but/except后省去to,如:
I can do nothing but wait. (有do)
I have no choice but to wait.(无do)