他们可能觉得累，所以尽管表面上平静，却可能容易发怒。

They may feel tired, and though outwardly calm, can be irritable.

《柯林斯英汉双解大词典》

因此，你的外在表现为容易发怒或紧张。

As a result, he or she may easily get angry or nervous.

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当你感觉饿的时候你很容易发怒，同样你感觉到压力巨大。

You’re irritable when you’re hungry; you also often feel stressed.

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but people are shorter-tempered, but just seem more irritable

但是人们脾气更暴躁，更容易发怒。

加州的天气 - SpeakingMax英语口语达人