knock on;knock at;knock over;knock

knock on;knock at;knock over;knock knock on knock into knock at knock up knock on与knock at的区别 knock on Knock on 和Knock at 有什么区别啊? knock at和knock on有区别吗? knock at 和knock on 有什么区别? knock at 和knock on怎么用?RT knock knock knock knock knock knock knoch at 和knock on的区别 knock at the door敲门应该是knock at the door,有时也看到有用knock on the door的,还有是不是可以直接说“knock the door呢? knock into sb和knock at knock at,knock onWhat's the differance?