根据首字母提示完成单词。   

    Many people may think that ain the zoo are happy and lucky, but most of them are sad. Do you know why? Animals ltigers, lions and bears usually lin forests or mountains. They run, jump, play wtheir children and catch small animals for f. But now they have to stay in cages or small rooms in the z. They do not have to find food by themselves, because the zookeepers feed them. They do nbut eat, walk and sleep every day. Their lin the zoo is quite dfrom that in the forests bthey are not free.