阅读短文，从方框中选择适当的单词填空。

themselves      lions      sad      in      food

Many people may think that animals in the zoo are happy and lucky, but most of them are__________. Do you know why?  Animals like tigers, ____________ and bears usually live in forests or mountains. They run, jump, play with their children and find small animals for____________. But now they have to stay in small rooms ____________ the zoo. They don’t have to find food by ____________ because the zookeepers feed them.