New Words：

knock [nɔk]
v.敲；撞；击；打
n.撞击；敲击；敲击声；敲门

Sample Sentences：

Someone is knocking at the door.
The falling bottle knocked him on the head.
The two rooms had been knocked into one (= the wall between them had been knocked down) .

Did you hear the knocks at the door?
When I fell I got a terrible knock on the head.