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众所周知,水对于人类是至关重要的。水是生命的源泉。人体的60—70%由水组成;一个人每在要饮用2—3公斤水;城市里每人每天的生活用水需250—500公斤,一个百万人口的城市每天约需生活用水20万吨以上。水是农业的命脉。一棵玉米从萌发到结实需200公斤水;一公顷棉花一生竞要500吨水;生产1公斤菠菜要50公斤水,1公斤小麦要1吨半水,1公斤大米要4吨半水,1公斤鲜牛肉要30吨水。水是工业的血液。现代工业生产尤其需要大量的水(见表)。
It is well known that water is of the utmost importance to humans. Water is the source of life. 60-70% of the human body consists of water; 2-3 kg of water is consumed by one person; 250-500 kg of domestic water per person per day in urban areas; about 200,000 tons of domestic water per day for a city with a million inhabitants the above. Water is the lifeblood of agriculture. A corn from germination to fruiting need 200 kg of water; one hectare of cotton life competing to 500 tons of water; production of 1 kg of spinach to 50 kg of water, 1 kg of wheat to 1 ton of semi-water, 1 kg of rice to 4 tons of semi-water, 1 Kg of fresh beef to 30 tons of water. Water is industrial blood. In particular, modern industrial production requires a large amount of water (see table).