21. The cakes are so delicious. He’d like to have ______ third one because _____ second one is rather too small.

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

22. Ladies and gentlemen, please fasten your seat belts. The plane______.

       A. takes off          B. is taking off                    C. has taken off           D. took off

23. This morning , Jim was the first to be here, _______.

       A. usually             B. like usual                 C. usual                       D. as usual