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_______ something to prevent him from littering.
A. would do          B. did do                          C. will do                         D. do
10.Earth  ____________  by the gravity of the Sun and orbits around it.
A. holds                 B. is held                         C. is holding                              D. held