A Change of Colour（在线收听）

    Yang Zhu，a famous philosopher，had a younger brother named Yang Bu，who went out dressed in white one day．It began to rain so Yang Bu took off his white clothes and returned home dressed in black．His dog，failing to recognize him，rushed forward to bark at him Yang Bu was angry and wanted to beat the animal“Don't beat the dog，”said Yang Zhu，“you would have acted in the same way．If your dog had gone out a white dog and then came home black all over，wouldn't you have thought it very strange？”
    Exercises：
    回答下列问题：
    ① Why did the dog rush forward to bark at him？
    ② What did Yang Zhu tell his brother？