收音机复读机上的“音量Volume”旋钮，能够控制声音的响度．它的实质是一个[ ]
A．电流表
B．电压表
C．变阻器
D．开关
答案：C
________works late, and is very busy when people go out to dinners.
A．A waiter
B．A bank clerk
C．A reporter
D．A nurse
