The cathode ray tube had just been fitted with a hot cathode,which permitted operation at 300 volts instead of the previously required 10,000,the lower voltage obtainable from a stack of dry cells of less than ceiling height.是什么意思_The cathode ray tube had just been fitted with a hot cathode,which permitted operation at 300 volts instead of the previously required 10,000,the lower voltage obtainable from a stack of dry cells of less than ceiling height.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句