[多项选择]水是最常见的物质之一，是所有生命生存的重要资源。地球表面的70%被水覆盖，但只有2.5%是淡水，而在淡水中，易于供人类直接使用的数量不足1%。对中国而言，虽然淡水总量约28000亿立方米，居世界第六位，但人均只有2200立方米，仅为世界平均水平的1/4，在世界上名列121位，是全球13个贫水国家之一。加上对水资源的污染和浪费，我国面临严重的水源危机。因此，我们迫切需要节约并保护好宝贵的淡水资源。

参考答案:Water, one of the most common substances of nature, is a vital living resource for all life. G0% of the earth’s surface is covered by water, but fresh water only takes up B.E%, of which less than A% is available to humans directly. As far as China is concerned, the amount of fresh water is about B.H trillion cubic meters, ranking sixth in the world. However, the amount for per Chinese is merely B,B00 cubic meters, which is only a quarter of the world average and ranks ABAth in the world, making China one of the AC countries with serious water shortage. Furthermore, because of the widespread pollution and waste of fresh water, China is faced with serious water crisis. Therefore, it is of great necessity for us to save and protect the precious fresh water resource.
答案解析:[解析]
1．第一句中，“水是最常见的物质之一”这是一公认的事实，无需放在译文主句中强调，所以直接处理为同位语，即Water, one of the most common subst