spark plug
noun [ C ] uk/ˈspɑːk ˌplʌɡ/ us/ˈspɑːrk ˌplʌɡ/
(ENGINE)
火花塞
a device in an engine that produces an electrical spark that lights the fuel and makes the engine start
(PERSON)
US中坚，激励者
a person who gives energy to an activity involving others
She's the spark plug of the team. 她是该队的中坚分子。