On top of sth. 完全控制，做得好

Do you think he's really on top of his job?

你觉得他把自己的工作能做好吗？

A: How is the new project going?

新项目咋样？

B: Don’t worry. I was on top of it while you were on vacation.

别担心。你度假不在的时候，我做得很好。

On top of it/that

而且，还（描述不愉快的事情）

We missed our flight, and on top of that we had to wait seven hours for the next one.

我们没赶上航班，而且下一班还得再等7个小时。

top n. 上衣

I need a top to go with these trousers.

我需要一件上衣配这条裤子。

From top to bottom 彻底

She searched the apartment from top to bottom for the missing letters.

为了找那些丢了的信，她把整个房子彻底翻了一遍。

On top of the world 极度开心

I’m on top of the world; I’ve just had a baby son.

我开心死了！我刚有了个儿子！