20．Do you think it _____ taking the trouble to explain a job fully to new employees?

　　　 A．worthy　　 　　　 B．worth　　 　　　　 C．worthy of　 　　　 D．worthwhile

19．-Does anyone force you to do so?

-No, I ____ for this work.

　　　 A．offer　　　　　　　　　 B．attend　　　　　　　　 C．volunteer　　　　　　 D．tend

18．Strong wind almost swept her down off the cliff. Luckily she ____ a tall tree there.

　　　 A．held onto　 　　　　 B．hold up　 　　　　　 C．hold on　 　　　　　 D．hold back

17．Undoubtedly, _____ measures introduced in the late 1980s, it is much safer than before.

　　　 A．in addition to　　 B．except for　 　　　 C．due to　　 　　　　 D．in exchange for

16．The room was full of dancers, all making last-minute _____ to their costumes.

　　　 A．accommodation　 　　　　　　　　　　　　　　　 B．adjustments　　 　　　　　　　　　　　　　 C．qualification　 　　　 　　　 D．commitment

15．I was surprised that Mom seemed to _____ Tracy's new boyfriend.

　　　 A．approve　　 　　　 B．be approved　　 　 C．be approved of 　 D．approve of