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【单选题】
长途光缆线路的维护工作中，正确的说法是：（）
A.
备用光缆全面测试每年四次
B.
光纤后向散射曲线检查，备用系统每半年一次
C.
仪表通电检查每年一次
D.
光缆线路衰减测量备用系统每年两次
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参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】Subways are underground trains, which usually operate 24 hours a day. They are found in larger cities and usually run between the suburbs and the downtown area. Maps and schedules are available from t...
A.
within downtown areas
B.
away from city centers
C.
in or outside big modern cities
D.
between suburbs and city centers