6.  (symbolise)

7. (form)

8.  (celebrate)

9. . (be)

10. (increase)

 11. Noise pollution happens. There is a change in animals’ living pattern. (leads to)

12. There are asthma, allergies and other respiratory illnesses when air pollution happens. (leads to)

-lead to death

 

13. Acid rain is dangerous. Trees’ leaves are damaged. (because of)

There are many causes of acid rain such as volcanic eruptions or fires ... But the main cause is still humans.

Humans burn a lot of coal and oil, which usually contains a large amount of sulfur in petroleum coal, while the air contains a lot of nitrogen.

The cause of acid rain is the increase in the amount of oxides of sulfur and nitrogen in the atmosphere caused by human activity. Cars, thermal power plants and some other plants that burn fuel release SO2 into the atmosphere. Smelters and refineries also release SO2. In exhaust gas, in addition to SO2, there is NO gas created by the atmosphere at high temperature of the combustion reaction. The fuels such as coal, oil and gas that we are using contain S and N. When burned in an atmosphere with O2 component, they will turn into SO2 and NO2, very soluble in water. In the process of rain, under the effect of environmental radiation, these oxidants will react with water vapor in the atmosphere to form acids such as H2SO4, sulfur acid, and nitric acid. They fall to the ground again with raindrops or remain in the atmosphere with clouds in the sky. It is these acids that make rainwater acidic

Alaska , a state in the USA, ___faces__ both the Arctic Ocean and the Pacific Ocean. (face)

2. In Adelaide, south of Australia, the sun __doesn't set___ until 9 p.m in summer. (not/set)

3. Although England several good football teams, it ___has won__ the World Cup only once. (win)

4. The famous Sydney Opera  House..........hai served...................as an arts centre since 1973. (serve)

5. There are about 750 million English speakers in the world, and this number……is increasing……fast. (increase)

6. The Statue of Liberty in New York is a monument which …symbolises........ freedom. (symbolise)

7. England, Scotland, Wales, and Northern Ireland together the ........form.............. United Kingdom. (form)

8. America.......has elebrated.............Thanksgiving Day on the fourth Thursday of November since 1864. (celebrate)

9. New Zealand ………is.……….divided into the North Island and the South Island. (be)

10. Over 670 million people have visited Disneyland since it opened in 1955, and the number ………in creasing…… fast. (increase)

7. England, Scotland, Wales, and Northern Ireland together the ........form.............. United Kingdom. (form)

8. America.......has elebrated.............Thanksgiving Day on the fourth Thursday of November since 1864. (celebrate)