答案：A

题目分析: 句意：教室的灯还亮着，你知道他们熬夜做什么吗。为即将到来的考试复习呢。what they stay up late for   他们熬夜做什么，why they stay out late为什么很晚不回家，when will they stop studying什么时候将停下学 习，how they work on their lessons他们怎么学习功课。根据To revise for the coming exams，可知答案选A。