三极管的开关状态是指三极管工作在（）。

A.截止区和放大区

B.放大区和饱和区

C.放大区和线性区

D.截止区和饱和区

The extension of the after part of the keel in a single-screw vessel upon which the stern post rests is called the（）.

A.boss

B.knuckle

C.skeg

D.strut