21. — Could I use your computer for a few minutes, please?
— ________. I’m not using it myself.
A. Come on B. It depends C. Go ahead D. That’s great
22. In recent years ______ global warming is becoming ______ concern for people all over the world.
A. the; the B. a; / C. /; a D. the; /
23. If the rain keeps falling, it will ________ our whole plan.
A. damage B. harm C. upset D. ignore
