用合适词的正确形式填空。每空一词。 (每小题1分，共5分)
Animals are our    1 . We can find different kinds of animals in the world.
__2 ____ animals only eat grass, for example, elephants and cows. And some animals only eat  3 _ , for example, tigers and lions. Animals can do many things for people. For example, elephants can help people  _4   some heavy(重) work. Children like animals very much, so they often play    5  dogs. They think dogs are very clever. Boys and girls, what animas do you like?