21. Animals that live on Tibetan plain have to survive in hard climate.
A.a; the B.the; a C. the; the D. a; a
22. People in the west make ___ a rule to buy Christmas presents for their relatives and friends.
A.this B. that C. it D. as
23. “Tommy, run! Be quick! The house is on fire!” the mother shouted, with____ clearly in her voice.
A. anger B. rudeness C. regret D. panic
