第一节：单项填空（共15小题，每小题1分，满分15分）
21. In face of failure , it is the most important to keep up good state of mood .
A. /; a B. a; / C. the; / D. /; the
22. Most animals have little connection with animals of a different kind , they hunt them for food .
A. if B while C. unless D. as
23.＿＿＿＿ Sunday, the students are at home.
A. Being B. To be C. It is D. It being
