阅读理解

　　Of all the things we eat and drink, water is the most important. Not many people realize this but it is quite true. The human body can go without food for a long time, but two or three days without water usually results in death.

　　Many people do not know how much water the human body needs to work properly and many people don't drink enough, especially in hot weather most people drink when they are thirsty, but we often need more water every day, but we do not need to drink this amount because a lot comes from food we eat. If we do not have enough water, however, we feel tired and many become ill. Do you know what the best drink is? It is cold water.

1．What's the most important of all things we eat and drink?

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2．The human body can go without ________ for a long time.

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3．Most people drink when they are________.

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4．The water the body needs comes from

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