Complete the text with the following sentences

a) Medical journals in Australia say two-thirds of the population alive today will develop some form of skin cancer.

b) Their low thermal conductivity made them ideal for coolants in refrigerators and air-conditioners.

c) The radiation kills off the plankton on which larger sea creatures depend.

d) The scientists who know about the ozone layer are worried.

e) These are the products which double in output every ten years.

In 1928, Thomas Midgley, a scientist and engineer in America, found a way to use chlorofluorcarbons (CFCs) as a refrigerant. They proved to be a valuable compound, stable, non-poisonous, non-corrosive, non-flammable.

1…... In the Second World War, CFCs were widely used as cleaning solvents and in plastic foam for food and drink containers, and the insulation of buildings.

2…... These products have contributed to the destruction of the ozone layer, the thin veil in the stratosphere which protects animals and plants from disease and, possibly, extinction.

Other man-made chemicals, apart from CFCs, are eating ozone molecules. Among them are halon gases used in fire extinguishers, aerosols, and refrigerators, and two compounds widely used as solvents: methyl chloroform and carbon tetrachloride. Their combined reaction on the ozone layer is devastating, allowing ultraviolet rays from the sun, known as UV-Bs, to bombard the earth. UV-Bs cause skin cancer.

3…... More than 250,000 of the continent's 16 million inhabitants will develop the deadliest of all, malignant melanoma.

UV-Bs can damage the immune system and leave you open to infectious diseases. They damage your eyes, burning the cornea, injuring the retina and generating cataracts. In southern Chile, blindness has begun to strike humans, sheep, rabbits and horses. 4…... In southern Chile a 12 per cent reduction in plankton has been measured.

5……. They give three reasons for their pessimism

1. ozone depletion is now general over the globe, and occurring twice as fast as had been predicted: according to reports, in the first two months of this year, parts of the ozone layer shrank by 20 per cent, and levels of chlorine, the ozone-eating chemical, were 70 times higher than normal;

2. depletion is now being caused by the CFCs released in the mid-1970s, and so the chemicals being released now will endanger our children;

3. no one knows what the cumulative effects of the depletion of the ozone layer will be, but they do know that things from now on are going to change very quickly indeed.