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【单选题】
⼈类听觉的适宜刺激是频率（ ）赫兹的声波。
A.
200～20000
B.
1000～4000
C.
16～20000 47
D.
1000～5000
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