多媒体通信技术是多媒体技术和通信技术的结合。
参考答案：对
进出口货物报关单备案号长度为( )位。
A．12
B．15
C．18
D．19
Since you have practiced so much in driving, there ______ be any difficulty in passing the road rest. [ ]
A. mustn't
B. shouldn't
C. shan't
D. needn't
