Have you ever heard of friendships among animals？ At a zoo in Germany, an unusual friendship developed （1）　　 a cat and a bear．

    No one is quite sure how the friendship first began．One day,some（2）　　（worker）in the zoo noticed a black cat was in the bear's cage（笼子）,and the two animals were playing together peacefully．They were surprised （3）　　well the small cat seemed to get along with the large bear． The bear keeper allowed the cat to stay with the bear． And later the pair and their unusual friendship（4）　　（become）a hot topic at the zoo．

    After several years, a new cage （5）　　（build） for the bear． However, the cat was still in the same cage, so it walked around （6）　　（angry） and cried to be with the bear． The bear keeper finally took pity on the cat（7）　　 let it stay with the bear． The cat and the bear got（8）　　（close） than before． They often sat together and shared meals in （9）　　 sun．

    Sometimes it may be natural for animals （10）　　 （have） their own ideas about who would make a good friend． These may surprise humans, who usually expect animals to form relationships with others of the same species．