bite one's head off千万不要理解为“咬掉...的头”，实际意思是“大发脾气，（为小事）严厉斥责，向某人恶言相向 ，把某人骂的狗血淋头，不客气（激怒地）答覆”。毫无理由地怒气冲冲地跟某人说话。

【例句】
Her boss bit her head off because of her mistake.
因为她犯的错，她被老板严厉批评了一顿。

I'm very sorry I lost my temper. I didn't mean to bite your head off.
很抱歉我发脾气了。我不是故意要生你的气。