knock at/on 敲knock into 撞到某人身上knock down 撞倒knock out of 把…敲出knock over 撞倒knock off 停止工作，休息1) The boxer soon knocked his opponent ________ __.2) The office stuff knocks _________ ___ at six every day.3) Try knocking __________ ___ the window and see if there is anyone indoors.4) He was so absorbed in his book that he knocked __________ _____ the car parked there.

Suddenly he heard someone（）gently on the window. A: knock B: knocking C: knocked D: to knock

A: Listen! There__________ someone __________ at the door.B: It must be your sister. A: is; knocking B: is; knock C: are; knocking D: are; knock

Knock a total of ______ times. Each knock ______. A: one B: two C: three D: four E: five

There was a knock on the door, but _____ answered it.

Listen!Someone____________(knock)atthedoor.

knock out（基因敲除）

I heard someone _______ loudly at the door while I was listening to the radio. A: knock B: knocking C: to knock D: knocked

中国大学MOOC: “Knock off early” means ( ).

While he the letter, he heard a knock at the door.