新视野大学英语视听说教程(第二版)第三册答案(3)

(6)from occurring

(7)law

(8)throw away

(9)fined

(10)trash

Task 2:River pollution

Script:

If you see dead fish floating on the river or notice that the water is discolored and smelly,

you know the river has been polluted, and there are four main possible causes for it.

First, fertilizer. If large amounts of fertilizer or farm waste drain into a river, the concentrations of nitrate and phosphate in the water increase considerably.Algae use these substances to grow rapidly, turning the water green.

This massive growth of algae leads to pollution. When the algae die, they are broken down by the action of the bacteria, which quickly multiply, using up all the oxygen in the water and therefore causing the death of fish.

Second, industrial waste. Factories sometimes discharge chemical waste into rivers. Examples of such pollutants include cyanide, lead,