1. Air......................, together with littering, is causing many problems in our cities today. A. pollute B. pollution C. polluting D. polluted 2. The road in front of my office is always .................... when it rains heavily. A. to flood B. flooding C. flood D. flooded 3. Singapore is famous for its .................... and green trees. A. cleanliness B. cleanly C. cleaning D. clean 4. In some English speaking countries, turkey and pudding are ............... food at Christmas. A. national B. historical C. traditional D. possible 5. The USA has a population of 304 million, and it’s the third ............. country in the world. A. smallest B. largest C. narrowest D. highest 6. The roof of the building .......................... in a storm a few days ago. A. damaged B. was damaged C. has damaged D. has been damaged 7. A severe tropical ...................... is called a typhoon. A. drought B. rain C. flood D. storm 8. As soon as the floodwater ...................... down, people ........................ their houses. A. went - cleaned B. had gone – cleaned C. went - had cleaned D. had gone – had cleaned 9. If I were you, I ..................... do something to prevent him from littering. A. would B. did C. will D. do 10. Earth .................. by the gravity of the Sun and orbits around it. A. holds B. is held C. is holding D. held 11. By the time we ........................ to the cinema, the film had started. A. gets B. had got C. has got D. got 12. When the policeman came there, the robber .................. A. had left B. has left C. left D. was left 13. All people who were without homes in the flood were provided with .................. accommodation. A. short B. temporary C. present D. instant 14. Seven of ten people prefer face-to-face ..................... when having a date. A. language B. contact C. code D. sign 15. When thermal pollution happens, the water temperature in streams, rivers, lakes and oceans ........................ A. changes B. keeps C. remains D. stays