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【单选题】
为防止最后一排座位距黑板太远,影响学生的视觉和听觉,后排距黑板的距离不宜大于( )
A.
6m
B.
8m
C.
8.5m
D.
10m
参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】Every year television stations receive hundreds of complaints about the loudness of advertisements. However, federal rules forbid the practice of making ads louder than the programming. In addition, t...
A.
TV stations always operate at the highest sound levels
B.
their sound levels are kept around peak levels
C.
their sound levels are kept in the middle frequency ranges
D.
unlike regular programs their intensity of sound varies over a wide range