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21.  It is          great fun watching          stand-up comedian standing in         

      front of the stage telling jokes.

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

22.           in a traffic jam for a long time is a rather boring and even annoying thing in a big

      city.

      A. Caught                  B. Being caught          C. Having caught           D. Catching