One of the most urgent environmental problems in the world today (17)__________ the shortage of clean water. Having clean drinking water is a basic human right. But acid rain, industrial pollution and garbage have made many sources of water (18)__________. Lakes, reservoirs and even entire seas have become vast proofs of poison. Lake Baikal in Russia is one of the largest lakes in the world. It contains a rich (19)__________ of animals and plants, including 1,300 rare species that do not exist anywhere else in the world. But they are being destroyed by the massive volumes of industrial wastes (20)__________ pour into the lake every day. Even where law existed, the government did not have the power to enforce them. Most industries simply ignore the regulations. The Mediterranean Sea occupies 1% of the world’s water surface. But it is the dumping ground for 50% of all marine pollution. Almost 16 countries regularly industrial wastes a few miles offshore. Water is free (21)__________ everyone. A few years ago people thought that the supply of clean water in the world was limitless. Today, many water supplies have been ruined by pollution and sewage. Clean water is now scarce, and we are (22)__________ beginning to respect this precious source. We should do something now.
- A. is B. are C. have been D. was
- A. clean B. polluting C. undrinkable D. inedible
- A. amount B. variety C. lot D. plentiful
- A. which B. who C. what D. where
- A. with B. to C. for D. on
- A. at first B. at once C. at last D. at least
