-6xn-3x2n分解因式正确的是[ ]
A．3（-2xn-x2n）
B．-3xn（2-xn）
C．-3（2xn+x2n）
D．-3xn（xn+2）
答案：D
Why are mobile phones popular in China, according to the speaker
A．They are considered as fashionable items.
B．They keep people closer to each other.
C．They are more convenient to users than fixed phones.
D．They are considered time-saving devices.
