C. causing                                                               D. having caused

8. Athletes ______   at the Olympic Games are supposed to be nonprofessionals.

A. who compete                                                       B. who are competing

C. who will compete                                                 D. who have competed

9. ______ Jack wouldn’

t take up the job, we might as well ask Richard to do it.

A. For                                                                     B. Since

C. While                                                                  D. Though

10. “You haven’t been to the Niagara Falls?”

   “______, I haven’t.”

A. Of course not                                                      B. No

C. Yes                                                                     D. Certainly