脉冲编码调制是一种将（）变换成（）的方式。
参考答案：模拟信号，数字信号
It’s important ____ the piano well.
A．of him to play
B．for him to play
C．of him playing
D．for him playing
治疗风热，肝热之目赤肿痛的首选药组是（）
A.菊花、麻黄
B.薄荷、柴胡
C.桑叶、菊花
D.蝉蜕、牛蒡子
E.蝉蜕、柴胡
