—Which do you prefer, a CD player or a walkman?

—I don't like _____. I prefer the new kind of MP4. [ ]

A. both

B. none

C. neither

D. either

浮选剂在浮选过程中发挥作用需一定的时间，一般而言，起泡剂发挥作用时间为（）。

A、5－8min

B、3－5min

C、1min