向端用户提供尽可能宽的网络接入是引起人们广泛关注的技术。 (46) 只能提供128kb/s的接入数据速率， (47) 则是通过电话双绞线向端用户提供更高信息传输带宽的一种接入技术，而采用 (48) 和电缆调制解调器也可获得和后者同样数量级的接入带宽。第3代无线通信的 (49) 可提供高达2Mb/s的接入数据速率。光纤到户，即 (50) ，是将来的一种发展方向。
A．GSM
B．HFC
C．CDMA
D．HDSL
参考答案：B
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| Ever since Jonathan had set up the house in Compton Street, he had looked after it very carefully. Before he left the house in the morning, he carefully closed all the __1__ downstairs, opened some windows to let the air in and locked the front gate. __2__ Jonathan did was tidy and orderly. One summer evening Jonathan returned home __3__ at five to seven exactly. When he opened the front gate, he immediately noticed something strange. There was a heavy footprint (脚印) in the earth in one of the flower beds. Jonathan was just going to blame (责怪) the milkman or the postman __4__ he noticed that one of the curtains (窗帘) in the front room downstairs was out of place. Jonathan never left anything out of place. He walked up to the front door and opened it quietly. He listened carefully for a few moments, but could hear nothing. The front-room door was half-open. Jonathan studied it carefully, __5__ if he had forgotten to close it that morning. He had never forgotten before. He stepped silently across the hall to the door and looked __6__ the room. The shadow (影子) of a man was clearly reflected on (映在) the far __7__ in the evening sunlight. He had been standing behind the door since Jonathan returned. Jonathan grabbed the door-handle (抓住门把手), __8__ the door quickly and turned the key. Then he __9__ the telephone in the hall and set about calling the police. The thief (小偷) tried to climb through a window to get out, but Jonathan had __10__ that. He attacked him with his umbrella, __11__ it as a sword (剑). Three minutes later the __12__ arrived there. Jonathan was a little angry that he had to have dinner later than usual, but on the whole he felt quite pleased with himself. | ||||
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