单项选择题
A．The United States. B．Some persons loving birds. C．People who think of the birds. D．Audubon's future generation.
A．They made laws that protect birds. B．They taught young people, helped pass laws that protect animals and so on. C．They tried to make the world better. D．Both Ｂ and Ｃ.
A．birds are important in our lives B．animals are important in our lives C．nature is important in our lives D．Audubon was especially interested in birds