当通过电话线连接到ISP时，因为电话线路输出信号为( )信号，计算机输出信号只能通过调制解调器同电话网连接。
A．数字
B．模拟
C．音频
D．模拟数字
参考答案：C
解析： 用户接入因特网的方法可以分为两类：通过电话线接入和通过局域网接入因特网。电话线路是为传输音频信号而建设的，计算机输出的数字信号不能直接在普通的电话线路上进行传输。调制解调器在通信的一端负责将计算机输出的数字信号转换成普通电话线路能够传输的信号，在另一端将从电话线路上接收的信号转换成计算机能够处理的数字信号。
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| Born in America, I spoke English, not Chinese, the language of my ancestors. When I was three, my parents flashed cards with Chinese 1 at my face, but I pushed them 2 . My mom believed I would learn 3 I was ready. But the 4 never came. On a Chinese New Year's Eve, my uncle spoke to me in Chinese, but all I could do was 5 at him, confused, scratching my head. "Still can't speak Chinese?" He 6 me, "You can't even buy a fish in Chinatown." "Hey, this is America, not China. I'll get some 7 with or without Chinese." I replied and turned to my mom for 8 . "Remember to ask for fresh fish, Xin Xian Yu," she said, handing over a $20 bill. I 9 the words, running downstairs into the streets of Chinatown. I found the fish 10 surrounded in a sea of customers. "I'd like to buy some fresh fish," I should to the fishman. But he 11 my English words and turned to serve the next customer. The laugh of the people behind increased 12 their impatience. With every 13 , the breath of the dragons (龙) on my back grew stronger-my blood boiling- 14 me to cry out. "Xian Sheng Yu, please." "Very Xian Sheng," I repeated. The crowd erupted into laughter. My face turned 15 and I ran back home 16 , except for the $20 bill I held tightly in my pocket. Should I laugh or cry? They're Chinese. I should feel right at 17 . Instead, I was the joke, a disgrace (丢脸) to the language. Sometimes, I laugh at my fish 18 , but, in the end, the joke is on 19 . Every laugh is a culture 20 ; every laugh is my heritage (传统) fading away. | ||||
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