Tham khảo tài liệu ôn tập tiếng anh phổ thông , ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | V. Our demand for water is constantly in creasing. Every year there are more and more people in the world. Faconries turn out more and more products and need more and more water. We line in a world of water. But almost all of it – about 97% - is in the oceans. This water is too salty to be used for drinking, farming, and manufacturing. Only about 3% of the world’s water is fresh. Most of this water is not easily available to man because it is locked in glaciers and icecaps. There is as much water on earth today as there ever or will ever be. Most of the water we use finds its way to the oceans. There, it is evaporated by the sun. It then falls back to the earth as rain. Water is used and reused over and over again. Is is never used up. Although the world as a whole has plenty of fresh water, some regions have a water shortage. Some regions are always too dry, and others too wet. A region that usually gets enough rain may suddenly have a serious dry spell and another region may be flooded with too much rain.
