21．Playing basketball is _____great fun; it also provides us with a chance to develop our sense of ______team spirit.
A．．a; 不填 B．不填; a C. a; the D不填；不填
22．In April, thousands of holiday-makers remained _____abroad due to the volcanic ash cloud.
A. sticking B. stuck C. to be stuck D. to have stuck
23. To help myself get to sleep, I have tried several ways but it seems that _______works.
A. none B. nothing C. neither D. all
24. ---Are you going to the concert?
---I’m not sure. I _____stay inside and watch it live on TV instead.
A. can B. might C. should D. must
25. On February 11, 2007, Drew Gilpin Faust was _____as the first female president of Harvard University.
A. appealed B. attached C. appointed D. transformed