【正确答案】正确答案： Water Pollution Today most water sources are so dirty / that people must purify water before drinking. / Water becomes dirty in many ways: / industrial pollution is one of them. / With the development of industry, plants and factories pour tons of industrial wastes into rivers every day. / The rivers have become seriously polluted, / and the water is becoming unfit for drinking or irrigation. / The same thing has also happened to our seas and oceans. / Scientists of many countries have done a lot of work to stop pollution. / Perhaps one day the people in all towns and cities will be drinking clean water. /