13. The struggle against the bird flu and the suffering _________ brought about have become a big concern across the world.

52. The struggle against sand storm will not end _____ victory unless we pay much attention to the balance of nature.

52. The struggle against sand storm will not end _____ victory unless we pay much attention to the balance of nature.

A. at                                   B. in                                   C. for                           D. With

13. The struggle against the bird flu and the suffering _________ brought about have become a big concern across the world.

       A. which has                 B. it is                          C. it has                       D. what is      

52. The struggle against sand storm will not end _____ victory unless we pay much attention to the balance of nature.