伺服系统是一种反馈控制系统，它由(冲)作为输入给定值，与输出被控量进行比较，利用比较后产生的偏差值对系统进行自动调节。

A. He is skilled and experienced.
B. He is very close to the manager.
C. He is always trying to stir up trouble.
D. He is always complaining about low wages.

A. He is always on time.
B. He is a trustworthy guy.
C. He is an experienced press operator.
D. He is on good terms with his workmates.