15. It’s ok to leave an electrical instrument on so long as you are using it, - 　　　, turn it off !

　 A. if not　　　　 B. if possible　　　　 C. if so　　　　 D. if any

14. The police are 　　　　the case of armed robbery that happened in the bank yesterday.

　 A. looking over　　　　　　　　　　　 B. looking up

　 C. looking into　　　　　　　　　　　 D. looking for

13. The orphans are brought up to believe they are different from other children, and are accustomed to 　　　　their emotions.

　 A. holding up　　　　　　　　　　　　 B. holding out

　 C. holding back　　　　　　　　　　　 D. holding down

12. Realizing I would be late, I quickly dressed my son and, 　　　　my bag, went to work.

　 A. carried　　　 B. having carried　　　 C. to carry　　　 D. carrying

11. The time is not far away 　　　　ordinary people can get on board a spaceship and take a trip to space.

　 A. as　　　　　 B. until　　　　　 C. before　　　　 D. when