表达练习：我们老师太无聊了，上课的时候忍不住打瞌睡

Our English is so boring. I’m always nodding off in class.

第1, Nod off 表示忍不住想睡觉打瞌睡。I was so tired from staying up all night that I kept nodding off throughout the day. 我那天没睡觉太累了，搞得我后来一整天都在打瞌睡。

第2，in class 表示在上课。He falls asleep in class everyday. 他每天上课的时候都会睡着。I’ll call you back later. I’m in class now. 我晚点给你回电话，我现在上课呢。