He can be really bad-tempered at times.

他有的时候脾气可真坏。

She gets very bad-tempered when she's tired.

她累的时候就爱发脾气。

He seems bad-tempered, but he's very soft-hearted underneath.

他表面脾气暴躁，实则菩萨心肠。

When his headaches developed, Nick became bad-tempered and even violent.

尼克的头疼起来时，他变得焦躁易怒，甚至暴躁。

My father, who had always been very self-controlled, became bad-tempered.

我那一向很有自制力的父亲，变得暴躁了。