1. This poem is Li Bai's masterpiece, which praises sincere friendship and expresses feelings of parting. It has been popular for thousands of years.
2. My friend said goodbye to me at the Yellow Crane Tower, and went on a long trip to Yangzhou in the sunny March when willow catkins were like smoke and flowers were like flowers. The shadow of the lone boat gradually disappeared at the end of the blue sky, only to see the rolling Yangtze River rushing towards the sky.
3. The first two sentences are intended to point out the characters, places, seasons and destinations of friends who bid farewell to each other.
4. From the poet's point of view, "The lone sail is far away in the blue sky, and only the Yangtze River flows across the sky" is a description of Meng Haoran sailing down the river. Li Bai stands in front of the building to see him off. As the ship goes farther and farther, the white sail on the ship gradually disappears at the end of the blue sky, where the water meets the sky.
5. Li Bai's poem neither recounts the depth and meaning of his feelings nor states how long he has been standing by the river to see each other off. However, the artistic effect he has received makes people feel deeply attached and poetic.