Who are the authors of these three fables?

(1) Who are the authors of the three materials? Li Bai, Du Fu, Bai Juyi. (2) Please summarize their respective poetic features in one sentence. Li Bai: unrestrained, fresh and elegant. Du Fu: Heroic and heroic, gloomy and sad. Self-styled: straightforward and understandable. (3) Considering their social background, consider why their poetic styles are different. Li Bai lived in the prosperous Tang Dynasty, and his poems were full of confidence and romance. Du Fu lived in the ups and downs of the Tang Dynasty and suffered an Anshi rebellion. His poems pay attention to the fate of the country and the suffering of the world, and faithfully record the face of the times. He lived in the late Tang Dynasty, which reflected the social reality and people's sufferings. (4) What qualities are they worth learning? Love the motherland, care about the country and people, care about people's feelings, etc.