1. To knock at/on 敲，击
I knocked at the door three times but nobody answered.
Someone was knocking on the window.
2. To knock around 漫游
He spent a few years knocking around Europe.
The college student knocked around the United States during his summer vacation.
3. To knock sb. down 打倒（撞到）某人
She was knocked down by a bus.
The boxer knocked his opponent
down twice in the first round.
4. To knock sth. down 推倒（拆掉、拆毁）建筑物
These old houses are going to be knocked down.
They knocked down the old factory to build a new one.
5. To knock off 停止某事，中断某事，（尤指）下班，收工
Do you want to knock off early today?
Let’s knock off for lunch.
6. To knock out 使入睡，昏睡，不省人事
Sam was drunk and knocked out his friend who stopped him from drinking.
The girl in the bikini knocked out the guys on the beach.
Tiffany knocked out three columns
7. To knock up 使怀孕
She got knocked up when she was on holiday.