21. As it turned out, ___ 2010 World Expo in Shanghai was ___ success.
A. /, a B. the, / C. the, a D. a, a
22. Selecting a mobile phone for personal use is no easy task because technology ___ so rapidly.
A. has changed B. will have changed C. is changing D. will change
23. ---I’m terribly sorry to interrupt, but may I use your phone? It’s rather urgent.
---Yes, ____ .
A. with pleasure B. no hurry C. it doesn’t matter D. of course
