One in every five young people has a sleep problem, so you're not alone. Getting enough sleep has become as important as eating vegetables and exercising regularly. It's very important for your body. Most young people only get seven hours of sleep each night, when they actually need nine hours. And making up for lost sleep during the week by sleeping in on weekends doesn't really work. In fact, sleeping late on weekends may actually do you more harm than good, if you have sleep problems.

　　What happens if you don't get enough sleep? If your sleep problem continues for a few nights, you could suffer serious problems. Lack of sleep can affect learning and memory. Worse, if your sleep difficulties last a long time, that could lead to anxiety or depression (抑郁).Therefore, you've got to have some healthy sleep habits. Below are some suggestions:

●Go to bed at the same time-including weekends, if possible.

●Wake up around the same time every morning. When you sleep late just one morning during the week, it may disturb your body clock. This will make it hard for you to sleep that night.

●Do something relaxing before going to bed.

●Exercise during the day. Don't exercise right before going to bed.

●Avoid drinking alcohol. Alcohol makes you excited. This prevents you from falling asleep or wakes you up during the night.

●Don't smoke. Smoking is always bad for the body. Smoking before bedtime keeps you awake.

　　If trying these tips over a couple of weeks does not help you, speak to your doctor. Do not take any sleeping pills without first asking your doctor. Many have strong side effects.

21. According to the passage, if you have sleep problems for a few nights, you could be_____. .

A. lonely B. serious C. forgetful D. depressed

22. The passage suggests that people with sleep problems should_________. .

A. eat vegetables and exercise regularly

B. make up for lost sleep on weekends

C. follow a fixed timetable for sleep

D. sleep seven hours every day

23. what's the main idea of this passage?

A. Many young people have sleep problems

B. Don't smoke before sleeping

C. How to keep healthy sleep habits

D. Smoking can make you awake

24. Which of the following is true according to the passage?

A. Sleep problems are serious among young people.

B. Sleeping late on weekends can make up for lost sleep.

C. Your eating habits will be broken due to lack of sleep.

D. You'll no longer have your sleep problem if you try the tips.

I once had a friend that was diagnosed with terminal cancer, and the news that he might only live up to six months was a great shock to him, his family, and his friends．However, in spite of the serious illness, he was initially（开始） determined to look into all available treatments that might cure or extend his life．I think that when you find yourself in such situations, you tend to look up