I have some problems finishing reading this book.
(finish doing sth)
I want to go to swim tomorrow.
(go to do sth)
It's not good for him to work so long time.
(be good to do sth)
You'd better go to help him.
('d better do sth)
Horses are useful animals.
useful 形容词,有用的
Stop talking Our teacher has something to tell us.
（have sth to do）
Taking exercise can keep you healthy.
（keep＋形容词）