当to作为动词不定式的标志时，后面加动词原形，作为介词的词性时，用v-ing的形式。to还可用于see to和come to等短语动词中。它还与某些带双宾语的动词连用，以引出第二个宾语。
例句
I wish to speak to the manager.
我想跟经理说话。
It pleased him to talk to her.
和她谈话让他高兴。
I had to go to the hospital.
我得去医院看病。
He loved her to sing to him.
他喜欢让她唱歌给他听。
I\'ve got to go to the john.
我得去趟卫生间。
