A、The body’s internal clock has been reset. B、The length of day and night has changed. C、The body has reactions to different env

W: Hey, Mike! Good to have you back! You look exhausted!
M: Hi, Linda. Yeah, I’m totally beat. I can barely keep my eyes open!
W: Was it a rough trip?
M: Well, it was actually pretty productive, but all the flying really got to me.
W: Ah, jet lag, the pain of business travelers.
M: The worst thing was adjusting to the time zones! It’s so hard to get used to the difference!
W: Yeah, it’s hard. You know jet lag only hits if you travel east-west or west-east. You could fly from Germany to Cape Town in South Africa and you wouldn’t feel anything.
M: Right, because it’s all in the same time zone.(1)Unfortunately for me, all my travel was between different time zones. I have to say: I’m really suffering! Why is jet lag so nasty?
W: (2)Travel between time zones basically resets your body’s internal clock.
M: So when you travel between time zones your body is thrown off its cycle?
W: Exactly!(3 - 1)Some experts say it takes a full day to recover from each time zone you cross.
M: Wow, that’s a long time.(3-2)I’m going to need a few weeks off!
W: That would be best, but unfortunately our boss isn’t quite that generous.
M: Is there anything I can do to make my jet lag less severe the next time I make an international trip?
W: (4-1)Some people take herbal medicine, but there’s really no solid proof that it works. Some people take sleeping pills and try to sleep for the whole flight.
M: I guess each person has to try and find the solution that works best for him.
W: Yeah, everyone is different. But I believe there are a few things that can definitely make jet lag a little easier to deal with.
M: Oh, yeah? Like what?
W: For one, don’t drink alcohol on flights. It dehydrates you and only makes jet lag worse.
M: Oh, I usually have a few drinks when I fly. Maybe I should stick to water next time.
W: (4-2)Water is best because you really need to stay hydrated, especially when you’re breathing the dry air in an airplane. Also, you should try to get on the local schedule as soon as you land.
M: I guess that makes sense.
W: Your body will slowly accept a new sleep-wake cycle.
M: (5)But the cycle is based on light from the sun, right? Then maybe I should take a walk in the morning and try to reset my brain to the new time for light.
W: Actually, that’s probably a great idea. And the exercise can’t hurt either.
M: I think I’ll try some of these ideas next time and see which ones work for me. Thanks for your input, Linda.
W: Sure! And have a nice rest tonight.
1. What do we know about the man’s business travel?
2. According to the woman, what is the cause of the discomfort from jet leg?
3. What can be inferred from the conversation?
4. Which is NOT mentioned as a solution to jet lag?
5. Why does the man intend to take a walk in the morning?