[电] electron-stream transmission efficiency
diàn zǐ liú chuán shū xiào lǜ ㄉㄧㄢˋ ㄗˇ ㄌㄧㄡˊ ㄔㄨㄢˊ ㄕㄨ ㄒㄧㄠˋ lv4