self-controlled
adjective usually approving uk/ˌself.kənˈtrəʊld/ us/ˌself.kənˈtroʊld/
自制的；有自我控制能力的
having strong control over your emotions and actions
He's always seemed very self-controlled, so I was amazed by his sudden outburst in the office. 他总是显得很有自制力，所以他在办公室突然情绪失控让我感到诧异。