综合填空。用方框中所给的单词的正确形式填空，使短文正确通顺，每词限用一次（每小题1分，共10分）

when, need, die, important, how, if, become, without, tired, hot

Of all the things we eat and drink, water is the most______. Not many people understand this, but it is quite true. The man’s body can go______ food for a long time, but two or three days without water usually makes people________.
Many people don’t understand how much water the man’s body _______ and they don’t drink enough, especially (特别) in _______ weather. Most people drink when they feel thirsty. They often need more water especially ________ they have sports.
______ we don’t have enough water, we may feel _______ and may _______ ill. Now you can see_______ important the water is.