阅读下面短文并回答问题，然后将答案写到答题卡相应的位置上（请注意题后词数要求）。
Good sleep is needed for good health. During sleep, your body repairs itself. Your immune system is built up. Don't shortchange（亏待，欺骗） yourself of the sleep you need. Here are someof an expert's tips for getting a good night's sleep.
1. Make sure your room is dark. Pull down the shades. Let no light of any kind in.
2. Before you go to sleep, ask your family not to turn on a light. Light breaks the sleep rhythm. Once broken, it's hard to get the sleep clock running right. As a result, you will not sleep well. You will wake up tired.
3. A hot bath just before bed is good. It makes you relax. You are at peace. This starts the desire for sleep.
4. During the day, ____________________.Even jogging(慢跑) will show good results. How about a good long walk? This will get your body to work. You will find that toward evening you will get that nice, tired feeling. Sleep then will come easily. Added to this, exercise is good for your health.
5. Here is what to do when you get up. Open the shades or blinds. Let the sun in. Open the  windows. Let the fresh air in. This sun and air get imprinted on your brain. The rhythm of being awake gets started. Your body clock is set for the day. That clock will let you know when it is the right time to go to sleep.
What does the underlined word ”It” mean? (Please answer within 5 words)
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What's the main idea of the passage? (Please answer within 15 words)
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Please fill in the blank in the paragraph with the proper words or phrases to complete the sentence. (Please answer within 5 words)
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Which sentence in the passage can be replaced by the following one? (Please answer within 10 words)          To be healthy, you need good sleep.
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How can we get a good sleep?(at least 3 suggestions) (Please answer within 30 words)
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