完形填空

　　When I was a boy of twelve, something stopped me forever from putting any wild creatures in a cage．

　　We lived in a village．Every evening the mockingbirds(仿声鸟)would come and 　　1　　 in the trees and sing．No musical instruments can produce a more 　　2　　 sound than the songs of the mockingbird．

　　I decided to 　　3　　 a young bird and keep it in a cage so that I would have my own private 　　4　　．

　　Finally I managed to catch 　　5　　 and put it in a cage．At first, the bird moved wildly about in the cage, but at last it 　　6　　 in its new home．I felt very pleased 　　7　　 myself and looked forward to some beautiful 　　8　　 from my little musician．

　　On the second day, my new pet's 　　9　　 flew to the cage with something in her mouth．The baby bird 　　10　　 everything she brought to it．I was pleased to see this．　　11　　, the mother knew better than I about how to 　　12　　 her baby．

　　The following morning 　　13　　 I went to see how my bird was doing, I was shocked to find it on the floor of the cage, 　　14　　 I had taken good care of it, but 　　15　　 had happened?

　　Arthur Wayne, a famous scientist, happened to be visiting my father at the time．Hearing me crying over the death of my bird, he 　　16　　 what had happened．"A mother mockingbird, finding her young in a cage, will sometimes bring it 　　17　　 food．She thinks it better for her young to 　　18　　 than to live in a cage．"

　　　　19　　 then I have never caught any living creature and put it in a cage．All living creatures have a 　　20　　 to live free．