What changes have taken place in the emotional tone of poetic images in Send Shen Zifu to Hedong? What are the advantages of the author's metaphor of lovesickness with spring scenery?

The first two periods indicate the time and place of farewell. "Liudu" is a true description of spring scenery, which not only paves the way for the following lovesickness, but also renders the environment and atmosphere of seeing off. In the ferry of Yangliuyiyi, when the spring is bright, I feel particularly depressed when I break up with my friends. This is to set off feelings with beautiful scenery. The ancients had the custom of folding willows to bid farewell, and the image of "willow" implied parting. "Few travelers" shows the quiet scene of crossing after leaving. Travelers are becoming more and more scarce, and only poets are still standing at the ferry, watching their friends go away reluctantly.

This is another contrast technique. Add a note to the sentence "teacher paddling":

Even the fishermen are shaking their oars and swinging to the curved shore near the water, ready to go home. The poet forgot to go home, and his body and mind were taken away by his departed friends.

The last two sentences describe that a friend left by boat, and the poet looked across the river, pink and green, and the spring was pleasant. At this time, he had a whim, and his heart felt infinite attachment and parting, just like the ubiquitous and endless spring in front of him, coming home with his friends from Jiangnan Jiangbei. At the same time, these two poems skillfully use metaphor, symbol, personification, fantasy and other techniques to write the spring scenery with emotion and intention. The richness and ubiquity of spring scenery make people truly feel the profundity, sadness and transcendence of the poet's farewell feelings. Acacia is abstract and intangible. Poets use spring scenery as a metaphor, which makes it vivid and concrete, and makes people feel it. The image of accompanying friends home in the spring scenery of Jiangnan and Jiangbei is fresh and unique, creating a profound and far-reaching artistic conception.