[电] hole-in-the-center effect

diàn dòng zhōng xīn xiào yìng ㄉㄧㄢˋ ㄉㄨㄥˋ ㄓㄨㄥ ㄒㄧㄣ ㄒㄧㄠˋ ㄧㄥˋ