A:四肢变成翼,翼是飞行器官
B:家鸽小肠很短,利于减轻体重,适于飞翔
C:家鸽为恒温动物
D:家鸽有双重呼吸,肺和气囊都可进行气体交换
She finished the novel and returned it to me in time.