16. All of my efforts to ______ peace failed at last.
A. reserve B. conserve
C. persist D. preserve
17. The laws to be made have to ______ to various special interest groups.
A. lead B. cater
C. satisfy D. serve
18. Four weeks ______ for making the necessary preparations.
A. has allowed B. allowed
C. were allowed D. was allowed
19. ______ in my present work, I would be quite willing to do what you ask me to.
A. Were I not engaged B. I were not engaged
C. Engaged I were not D. Were not I engaged
20. It’s ______ on you to advise your students before they leave school.
A. obliged B. incumbent
C. satisfactory D. specific
