on top of用法及例句

　　例句：

　　He gets commission on top of his salary.

　　他除了薪金之外還拿傭金。

　　He was sound asleep on top of the covers.

　　他在床單上睡得很香。

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

　　你認為他真的能做好他的工作嗎？