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

Many human activities over the last 200 years have been responsible (22) ________ polluting the air and damaging people’s health. Automobile engines and power plants burn combustible (23) ________ like gasoline and coal and allow toxic gases and smoke to escape into the air. Some pollutants destroy the ozone layer, which is the thin blanket of gases that (24) ________ Earth from the Sun’s dangerous ultraviolet rays. Other pollutants contribute to (25) ________ warming by adding to the planet’s natural greenhouse effect. Still others create acid rain, a phenomenon that has disastrous (26) ________ on lake and forest habitats. Air pollution is not limited to industrial areas. Depending on the direction of the wind and its force, air pollutants may (27) ________ spread to other countries very far from the source of the pollution.

Big cities like Los Angeles and Mexico City are often covered by smog, a fog that occurs (28) ________ air pollution. In 1952, the City of London, England, was enveloped by smog so thick that people on the streets had to feel their way around by (29) ________ the walls of buildings.

- combustible (adj): dễ cháy                           ultraviolet ray  (n phr): tia cực tím

22. A. with B. of C. to D. for

23. A. fuels B. means C. chemicals D. matters

24. A. covers B. protects C. stops D. damages

25. A. environmental B. thermal C. global D. temperature

26. A. affects B. causes C. sources D. effects

27. A. never B. ever C. even D. hardly

28. A. in spite of B. because of C. instead of D. due of 

29. A. climbing B. walking C. touching D. putting up