21. Two people said that ______ UFO was traveling from east to west when they saw it at ______sunset.

  A. the; /                 B. /;the                         C. an;/                          D. a; the

22. The workers are ______ the building of the new streets in Yangcheng in order to complete them ahead of time.

  A. taking up           B. making up                 C. stepping up               D. putting up

23. Don’t be too ______ about things you are not supposed to do.

A. brave                B. bright                       C. curious                     D. uncomfortable

24. I always can’t help ______ people in trouble a hand. But I’m very busy today that I can’t help ______the work with you.

   A. to give; to do      B. giving; doing             C. give; do                    D. giving; do