一只氖管的起辉电压（达到或超过起辉电压后氖管会发光）与交变电压V的有效值相等，若将这交变电压接到氖管的两极，在一个周期内，氖管的发光时间为
Whether she wins or whether she l this is her last game．
A the traffic was heavy，we got to the railway station on time．
He always arrives e than others， as he has the key to the classroom．
China has a history of more than five t years．
They've been good friends s they were little kids．
V的有效值相等，若将这交变电压接到氖管的两极，在一个周期内，氖管的发光时间为 
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