21. Rock climbing is ___ great fun. You will get close to ____ nature and take adventures at the same time.
A. /; / B. a; /
C. a; the D. /; the
22. —Do you think I should accept his invitation, Jim?
— If I were you, I certainly would.
A. None of your business. B. It depends.
C. Why not? D. I don't think so.
