So______ that most parents are too worried to let their kids travel alone at the beginning of the new term.

A．is the distance great

B．great the distance is

C．the distance is great

D．great is the distance

对于重要事情，我们常说“口说无凭”，因为口头传达效果较差，这属于沟通通道障碍中的( )。

A．外部干扰
B．沟通渠道过长
C．沟通媒介选择不当
D．几种媒介相互冲突