21. --- I’d like to see the movie very much, but I have no money with me.

--- That’s OK. My _____ this time.

A. offer                    B. treat                    C. promise               D. service

22. In recent years _____ global warming is becoming ___ concern for people all over the world.

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

23. The group has been teaching students how to spend money wisely and offer financial advice to ____ in debt.

A. them                    B. that                     C. ones                     D. those