我很愿意，但我那天下午有个考试。

I'd love to, but I've got an exam that afternoon.

youdao

不要扰乱我的学习。我明天有个考试。

Don't distract me from my studies. I have an exam tomorrow.

youdao

查尔斯：我差点忘了，我今天有个考试。

Charles: I almost forgot. I have an exam today.

youdao

And there will be a different exam in the afternoon, but I think it only makes sense for you not to discuss the paper with people that are taking it in the afternoon.

在下午会有个不同的考试，但是我想仅仅是对你有意义,而不是和别人,讨论下午正在考的试卷。

麻省理工公开课 - 固态化学导论课程节选