I was born （出生） in a small river. When I was young，the river was my home. I didn't know my father or my mother，but I had many brothers and sisters. I swam and played with them.  
      At that time I didn't look like my father or my mother. I had no legs，but I had a long tail. So I looked like a fish.  
      Then my tail became shorter and shorter. And now I have four legs and a very short tail.  
      I know I'm going to have no tail at all soon （不久）. I'm going to be like my father and my mother. Then I'm going to jump out of the water. I'm going to live on land and in the water，too. I'm going to eat a lot of insects （昆虫）—a lot of bad insects. Can you guess what I am？