有do不加to有哪些句型?

楼主问的是前有do后无to的情况有哪些句型吧？
(1)连词连接两不定式前面的有do后面的to do的to省略，如：
I have nothing to do but do 和你说的那个
(2)用is连接，不定式作表语是前面主语有do时后面表语to do的to省略，如：What I want to do is do
(3)注意这里说的前有do后无to的前面的do要是实意动词do,不能是助动词do~~~

表示强调的时候，I do agree with you.
can后面不加to, I can't do this.
would，suggest, help后面都可以跟原型，Would you please do me a favor?
I suggest you do this.
He help me do this.

have better (not)do

表示强调的时候，
和情态动词后直接原型动词

有些是前有do后省略to的.