根据上下文填上正确的介词或副词
1.He did not know how to fight, but he knocked the boxer ____.
2.This flowerpot is broken, Who knocked it ____?
3.I knocked ____ early yesterday and went to a football match.
4.Listen!Smoeone is knocking ____ the window!
參考答案:1,down
2,out
3,up
4,at
