“黄河之水天上来，奔流到海不复·回。”诗句中的“天”和“海”分别是指    (    )

    Li Dong is a schoolboy. He's twelve. He lives in Beijing. He gets up at 6:30. He reads English and Chinese in the morning. He has breakfast at 7:00. In the afternoon, he has three classes. He often does the homework after dinner. Li Dong likes playing football. His mother's hobby is planting flowers. His father is interested in collecting stamps. He often shows the nice stamps to Li Dong and his mum. They like the stamps very much.