阅读以下关于ADSL宽带接入Internet的组网说明，根据要求回答问题1～5。
[说明]
某山区中学决定采用非对称数字用户线(ADSL)宽带接入Internet，以提高其行政办事效率，并要求能使内部30台计算机通过代理服务器访问Internet，其拓扑结构图如图2-25所示。电信部门分配给该中学的公网IP地址为202.117.12.36/30，DNS的IP地址为202.101.98.55；该中学内部网络使用的IP地址块为192.168.1.0/24。
[问题1]
ADSL技术可以充分利用现有电话线网络，只要在用户端加装相关设备即可为用户提供服务。请从以下术语选择适当的编号，将图2-25拓扑结构中(1)～(4)空缺处的设备名称填写完整。
供选择的答案：
A．程控交换机 B．普通二层交换机
C．用户端ADSL Modem D．ATU-C模块
E．局端ADSL Modem F．用户端滤波器
G．局端PS H．代理服务器
参考答案：C
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| It was a cool October evening.Excitement and family members__1__the hall.I was only a 7yearold girl, but I was the center of__2__.Finally, after weeks of preparation, I would__3__all my hard work in a dance performance.Everything would be__4__-so I thought.I waited backstage all__5__in my black tights with a golden belt.In a loud and clear voice, the master of ceremonies__6__that my class was next. My dance class was doing a routine on wooden boxes two feet by two feet, facing the__7__.All I had to do in the next move was put one foot on the box next to mine and keep my other foot on my box.It really was an__8__m  ove.I was concentrating so much on__9__the huge smile on my face and holding my head up that I did not look__10__I was going.I missed my partner's box altogether and__11__. There I was standing on the stage floor when my classmates were on top of their boxes.I could hear giggles(咯咯笑)coming from the audience, and I felt the__12__rush to my face.I remembered my dance teacher had told us, "  If you make a mistake, keep smiling so the audience will not__13__."I did my bestto follow her__14__as I continued with the routine. When th  e curtain dropped, so did my__15__for the evening.I__16__bitterly, tasting the salt from thetears that streamed down my face.I ran backstage, but no one could__17__me down. Recently I realized I had been a__18__that night.I was__19__, but I fought the urge to run off the stage.__20__, I finished the routine with a smile on my face.Now when friends and family laugh about the time I slipped during a dance performance, I can laugh to  o. | ||||
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