“沉不住气”常见的英文表达有 “lose one's temper”、“get impatient”、“be unable to keep one's cool” 或 “can't control one's emotions” 等，具体使用可根据语境和表达重点来选择：
lose one's temper：强调因无法控制情绪而发火、发脾气，侧重于情绪爆发这一行为。
例句：He lost his temper when he heard the bad news.（听到这个坏消息时，他沉不住气，发火了。）
get impatient：侧重于表达因长时间等待、事情进展不如意等原因而变得缺乏耐心，情绪开始急躁。
例句：The kids got impatient waiting for their turn on the swing.（孩子们在等待荡秋千的时候沉不住气，变得不耐烦了。）
be unable to keep one's cool：意思是不能保持冷静、沉着，更强调在面对压力、挑战或意外情况时，无法维持冷静的状态。
例句：She was unable to keep her cool during the heated debate.（在激烈的辩论中，她沉不住气，无法保持冷静。）
can't control one's emotions：强调无法控制自己的情绪，情绪处于失控状态。
例句：When criticized, he can't control his emotions and often responds angrily.（当受到批评时，他沉不住气，常常愤怒地回应。）