Have you ever been to the zoo? There are different kinds of 1 in the zoo. We can see the zoo keepers (饲养员) give them food to 2 . They don't have to 3 food by themselves (他们自己). They just eat, walk and sleep 4 day. So many of us think the animals in the zoo are 5 and lucky. But most of them are sad. Why? They are not 6 in the zoo.

    Animals 7 elephants, monkeys and tigers usually live freely and happily in forests or mountains. Tigers, for example, run, jump, play with 8 children and catch small animals for food. But now they 9 stay in small cages（笼子） in the zoo. Their life in the zoo is quite 10 from their life in the forests. Now many people think more animals should go back to forests and mountains so that they become free and happy again.