Play by the rules, especially if you are studying English to sit an exam.

要遵守游戏规则，尤其是你正在为了参加考试而学习英语。

Your English writing skills are obviously important if you're sitting an exam.

如果你要参加考试的话，英语写作技能显而易见是非常重要的。

It felt like I was about to sit an exam I hadn't prepared for.

感觉就像我即将参加一场我没有准备的考试。

And it can be used as a way of saying stop like when you're playing a game or when you're sitting an exam and the time finishes.

当你在玩游戏或者是参加考试，时间到了的时候，这也可以用作叫停。