[电] characteristic curve of electron tube
diàn zǐ guǎn de tè xìng qū xiàn ㄉㄧㄢˋ ㄗˇ ㄍㄨㄢˇ ㄉㄜ˙ ㄊㄜˋ ㄒㄧㄥˋ ㄑㄩ ㄒㄧㄢˋ