一般为提高放大器的载噪比,即提高放大器的输入电平,干线放大器的输入范围应为()dB。
A、68-75
B、70-72
C、72-75
D、75-78
参考答案:B
— What are the people in Korea supposed to do when they meet for the first time?
— They are supposed to ____. [ ]
A. kiss
B. bow
C. say hello
D. shake hands
钢材含磷高具有冷脆性,一般生铁含磷愈高愈好。()