(2) The main content of the article is to write about the river, but it is written that Uncle Gao cooked fish for us to think of catching fish by writing about eating fish, and to think of the past and future of the river by catching fish.
(3) The author combines Teresa Teng's singing with the picture in front of him, so that readers can enjoy beauty in hearing and vision, and thus they like the river more emotionally.
(4) Writing the last paragraph is to write about the great changes of the river by comparing the past and the present, so as to express his feelings of remembering the past and advocating nature.