不定式to do是动词的一种非谓语形式.在句子中有需要时一定要用,如一些及物动词后用作宾语.不及物动词后用作状语,系动词后用作表语,还可作主语,补语,如
I want to go there.
He came to see me .
My task this afternoon is to clean my room.
To see is to believe.
Our teacher told us to recite all the new words.
在使役动词和感观动词后用不带to的不定式作补语,如
Let's play.
I often hear him sing this song.
They made the workers work ten hours a day.
但被动语态中一定带to,如
The workers were made to work ten hours a day.