下列关于ITU V.90调制解调器(Modem)的特征描述，正确的是()。
- A.下载速率是56kb／s，上传速率是33.6kb／s
- B.上、下行速率都是56kb／s
- C.与标准X.25公用数据网连接，以56kb／s的速率交换数据
- D.时刻与ISP连接，只要开机，就永远在线
正确答案及解析
正确答案
解析
CCITT V.90：33.6Kbps上行，56Kbps下行
CCITT V.92：48Kbps上行，56Kbps下行
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