题目

阅读理解 In our town, there is a big zoo with a lot of animals in it. There are so beautiful tigers and two old lions. They eat a lot of meat every day. There are also two big elephants and one baby elephant. The elephants are kind animals. They eat a lot every day. They like children. Children often give them bread and bananas. Elephants like bananas best.    In our zoo there are also brown bears, black bears and white bears. They stand on their hind legs, hold up their fore legs and ask for food. They like cakes very much. There's also a children's corner in our zoo. Childr比17大又比20小的数是（_____）和（_____）。