-- l'm always a little nervous when I talk to Mr. Smith.

--            _____ He is strict, but he is kind to his students.

-_,

A．That's right

B．What a pity

C．Fake it easy

D．Take your time

方向控制阀的表示方法中，压缩空气的输入口一般用字母（）表示，或用数字（）表示。