9. Humans, dogs elephants and dolphins are all ___________, but birds, fishes, and crocodiles are not.

            A. single cell                B. sea animals              C. mammals.                D. krill

10. Tropical rain forests used to cover 10% of the earth ___________.

            A. surface                    B. seabed                     C. undersea                  D. floor.

11. Many species of animals and plants today are ___________.

            A. endangered              B. in risk                      C.  danger                    D. under danger.

12. A tropical rain forest, once destryed can never be ___________.

            A. recovered                B. replaced                   C. repaired                   D. regenerated.

13. He was wearing a heavy raincoat to ___________ himself.

            A. conceal                    B. protect                     C. cover                       D. wrap

14. You ___________ to go to bed late.

            A. shouldn’t                 B. oughtn’t                   C. mustn’t                    D. can’t

15. The UK is devided ___________ four parts : England, Scotland, Wales, and Nortern Ireland.

            A. between                   B. among                     C. into                          D. for

16. The sea is poluted, which ___________ sea plants and animals.

            A. dangers                    B. dangerous                C. dangerously             D. endangers

17.  I think you ___________ apologize for your behavior.

            A. should                     B. ought                       C. shall                         D. have

18. The life ___________ of sperm whale can be up to seventy years.

            A. period                      B. length                      C. distance                   D. span

19. I wonder where Mai is, She should ___________ here by now.

            A. be                            B. to be                        C. being                       D. have been