21. In 1948, three American scientists invented ______ transistor, which is ______ small electronic device to control an electric current.

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

22.  I would appreciate ______, to be frank, if goods could be delivered as soon as possible.

   A. you                B. this                      C. it                  D. myself

23.  —What do you think of Harry Potter and the Philosopher’s Stone?

—Fantastic. Steven Kloves ______ each character in the movie impressive through lively dialogues and fascinating plots.

   A. makes           B. would make            C. made            D. had made