On Protection of Water Resources
Seven-tenths of the earth is covered with water. That may， at first， sound like a huge amount of water. But do you know only 2.53% of it is fresh water？ Furthermore， most of the fresh water is at the North Pole and South Pole. This means only a limited amount of water is available to human beings. A man can live without food for six or seven days， but he can live no longer than three days without water. Because water is such an important resource for our existence， we must learn to save and protect the water that we have. Though water is very important in our lives， [However，] （1） many people still waste water. They use much more water than they need， and so do some factories， which waste thousands of gallons （加仑） of water every day. Today [Moreover]（2 ） we are faced with another grave （严重的）situation， which will speed up the shortage of water. With the development of industries， much water has been polluted. Some factories pour unprocessed （未处理过的） dirty water into rivers or lakes. As a result， those rivers and lakes are so polluted that the water in them can no longer be drunk or used. Having become a big problem， water pollution has attracted many people's notice. From the example of Shanghai [Take Shanghai for example ]， （3 ） we can see how important ， yet difficult， it is for us to protect water. As one of the industrial centres of China， Shanghai is short of water even though it locates [is located] （4） at the mouth of the Yangtze River， an area with abundant water resources. Each year， factories， hotels and farms in or around Shanghai discharge （排放） a huge amount of sewage （污水） into the rivers that run through the city. So its water quality is deteriorating （恶化） . The water in some of the rivers is no longer fit for drinking， and it contains so many poisonous elements （有毒物质） that it isn't even used to water the crops. The Government of Shanghai had to move the water intake to the upper reach [reaches ]（5）of the Huangpu River in 1970's because t
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