sb to do sth可做哪些句子的成分要有例子，

sb to do sth为不定式的复合结构，做宾语 如advise sb to do sth
eg. Our teachers often tell us to study hard.
He asks me to have a rest.

to do 就是不定式,接在某些动词后面的,七八年级的不定式一般表示 目的ask sb to do sth 要某人（去）做某事allow sb to do sth 允许某人（去）做某事make sb to do sth 要某人（去）做某事help sb to do sth 帮助某...