动词knock构成的短语动词

    1．knock at/on敲(门、窗等)

    e.g. Yon should knock at/on the door before coming in．

    2．knock down撞倒，拆掉

    e.g. They make sure the cows not knock the young trees down or eat the leaves.

    3．knock off把…撞掉下来

    e.g. A child ran into the street and knocked the woman off her bicycle．