单选题 .  Questions 5 to 8 are based on the conversation you have just heard.
5. 
【正确答案】 D
【答案解析】[听力原文]
   M: I'm so tired, I can't see straight.
   W: You've been tired a lot lately, haven't you?
   M: Well, for the last few weeks, I have had to stay up most of the night to observe star configurations for a project for my astronomy class. It's awful! No matter what time I go to bed, I always wake up at 6 a.m. That's the time I usually get up.
   W: Your biological rhythms probably haven't been adjusted to your new schedule. I've read that some people have a lot of trouble when their sleep rhythm is so interrupted. Even sleeping pills don't help them.
   M: I know. In fact I've heard there are now several special treatment centers for sleep disorders across the country. Some people sleep too little. Some people sleep too much. Some walk in their sleep.
   W: I'd like to find out how they treat problems like that. Maybe you should go to one of those centers.
   M: Not me. After next week, my project will be finished and I'll go back to my regular hours. Now I know for sure that I don't want to be an astronomer.
   What has the man not been able to do recently?
推理题。对话中男士说到由于要完成天文学课的一个课题不得不连续几个星期熬夜。由此可推知男士最近无法得到足够的休息。故选D。