21. Though there are such problems ______ heavy traffic and dirty streets, ______ lots of people the city remains the most wonderful in the world.

     A. to...as                 B. as…to               C. like…for                  D. that…as

22. The writer presents at least three to five adventures ______.

     A. to make the story more excited          B. making the story more excitement

     C. to make the story more exciting         D. making the exciting story more