【練習(xí)】

The growth of the world’s population and its pressure to resources __1

threaten to change the quality of life as we know it. It takes __2

100,000 years of human existence for the world to reach its 1997population of 5.85 billion people. The increase of 80 million people　in 1996 alone is the equivalent of a new U.S population every 3.4years or new Canadian population every 138 days. The UN population Fund predicts that by the year 2050, the world population have __3

exploded to 10 billion people. This would double in less than a century the already bulging population who existed when it reached __4

5 billion in 1987. The chemicals we spew into the air also cause disease.
For example, they attack the Earth’s ozone layer, which helps shield the Earth away the Sun’s deadly ultraviolet rays. It is well established __5

that the ozone layer has thinned considerably during recent decades.Concomitantly, the rate of new cases of the dead skin cancer, __6

melanoma, has grown dramatically from 1,168 of each 100,000 __7

Americans to 3,650. This 213 percent increase means that 40,300 Americans diagnosed with melanoma in 1997 and 3,650 died of the __8

disease. There are some scientists who believe that pollution is even threatening the ability of humans to produce. Chemicals which are __9

used to make pesticides, plastic, and other products are finding their ways into the human food chain through fish and even through __10

breast milk.

（責(zé)任編輯：liushengbao）