题目

-The TV is too noisy, would you mind        a little, please?--Sorry, I will do it right away. A．turning it off B．turning it onC．turning it downD．turning it up 答案：C解析:略已知函数，则a的所有可能值组成的集合为（ ）A．B．{1，}C．{-}D．{1}