March 21 is World Sleep Day.It reminds us to think about our sleeping habits and try to sleep better.How much do you know about sleep？
   Why do we need sleep？
   Nobody has the perfect answer to this question.Scientists did tests on rats.If rats don't sleep for over four weeks，their bodies become colder and smaller.And later，they die.
   How much sleep do we need？
   Different people need different amounts of sleep.Many surveys show that adults need to sleep about 7 to 8 hours a day.But younger people need more sleep.Doctors advise 10 hours for primary school students，9 for junior high students and 8 for senior high school.
   Do we always dream in sleep？
   Most of us dream every night.Sometimes you can remember your dreams.But if your sleep is deep enough，you may not remember your dreams.
   Does sleeping a lot on weekends help？
   Many people feel like they don't get enough sleep on weekdays，so they like to sleep for long hours on weekends.But does this make up for the loss？Doctors don't think so.You may feel better for a short time，but your body is already hurt.What's worse，this changes your body clock.The next day，you may find it hard to fall asleep.
   How can we sleep better？
   There are several ways you can do.你可以在睡覺前喝些牛奶。Comfortable bedding also helps.
（1）回答問題：
What does World Sleep Day remind us？

To think about our sleeping habits and try to sleep better.

To think about our sleeping habits and try to sleep better.

（2）將文中劃線的英語句子譯成漢語。

對這個問題，沒有人有完美的答案。

對這個問題，沒有人有完美的答案。

（3）從文中找出與下面所給句子意思相近的句子。
Everyone's sleep needs are not the same.

Different people need different amounts of sleep.

Different people need different amounts of sleep.

（4）回答問題：
What does the underlined word"it"in the Paragraph 9 refer to（指的是）？

To fall asleep.

To fall asleep.

（5）將文中劃線的漢語句子譯成英語。

You can drink some milk before you go to sleep.

You can drink some milk before you go to sleep.