A、Lack of moisture. B、Intension of radiation. C、Shortage of sleep. D、Misuse of medicine. A

W: Hi, Tom.(12)How’s your chemistry paper going?
M:(12)It’s coming along. But I’ve been staring at this computer screen for hours and my eyes hurt.
W: Yeah, doing that can make your eyes feel really dry and tired. You should take a break.
M: I can’t. I have to get this paper written. It’s due tomorrow.
W: You know, I read about computers and eye problems recently. The article says that they are usually caused by not moving your eyes enough.
M: Moving? I thought I just needed new glasses.
W: Nah. When you move, the movement of closing and opening your eyes helps make your eyes moist.(13)It’s the lack of moisture that causes the problem.
M: Oh, that makes sense. But what does it have to do with the computer?
W: People who use computers tend to stare at the monitor and move less often than they normally would. That leads to dry annoyed eyes.
M: Well, that’s certainly how mine feel now. They really hurt.
W:(14)The article I read about office workers found that the workers averaged 22 moves a minute when relax, but just 7 a minute while looking at text on a computer screen.
M: Wow, that’s quite a difference.
W: They also kept their eyes open wider, which means that moisture vanishes more quickly.
M: I wonder if using some kind of eye drops would make them feel better.
W: That might help.(15)But the best prescription is to take a break and rest your eyes.
M: Ok. Let s go get some coffee. I can finish this later tonight.