题目

______China's success in dealing with desertification, the United Nations Environment Program believes the country is a good example for others to follow. A . In the absence of B . In the light of C . In the place of D . In the case of 答案：B已知为实数，那么等于______A. 　　　　　　B. 　　　　 C. － 1　　　　　 D. 0