As we all know, looking away from people or yawning will, _______, make us appear to be uninterested.

A．for one thing

B．by all means

C．in most cases

D．at one time

调制解调器的作用是( )。

A．把计算机信号和音频信号互相转换

B．把计算机信号转换为音频信号

C．把音频信号转换为计算机信号

D．防止外部病毒进入计算机中