Who is_______(knock)on the door?

Who is_______(knock)on the door? Who is_______(knock)on the door? 解释下这句话Knock,knock jokesKnock,knock jokes是现在美国人长说的,原台词是knock,knock,knock,who is there? Who is _____ ( knock It is me. knock knock knock knock knock knock this flowerpot is broken .who knocked it___ knock over knock off 有什么区别 , Knock!Knock!Knock!歌词 knock on;knock at;knock over;knock A knock on the door!Who --it be?-A knock on the door!Who __it be?-Maybe the milkman.A.can B.mustc.mayD.will knock off和knock knock into ,knock down Knock Knock是什么意思 knock knock joke