斜坡式数字电压表的优点是成本低、线路简单，缺点是精度不高。
参考答案：对
___ _ I feel pity on them, I can’t really do very much to help them but contribute my pocket money.
A．While
B．As long as
C．When
D．Where
简述秦汉秘书的选拔与任用。
