Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word for each of the blanks.

One of the most urgent environmental problems in the world today is the shortage of clean water. Having clean drinking water is a basic human right. But acid rain, (1)__________pollution and garbage have made many sources of water undrinkable. Lakes, reservoirs and even entire seas have become vast pools (2)__________poison. Lake Baikal in Russia is one of the largest lakes in the world. It (3)__________a rich variety of animals and plants, including 1,300 rare species that do not exist (4)__________else in the world. But they are being destroyed by the massive volumes of toxic effluent which (5)__________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 (6)__________1% of the world's

water surface. But it is the dumping (7)__________for 50% of all marine pollution. Almost 16 countries regularly throw industrial wastes a few miles (8)__________shore.

Water is free to everyone. A few years ago, people thought that the supply of clean water in the world was limitless. Today, many water supplies have been (9)__________by pollution and sewage. Clean water is now scarce, and we are at last beginning to respect this precious (10)__________. We should do something now.

(Source: v 14ilovetranslation.com)

Điền vào số 2

A. on

B.in

C.of

D. to