What are the characteristics of the third and fourth sentences in Meng Haoran's poem "Sending Du Fourteen Down to the South of the Yangtze River"

The sun is about to set. Where will the long-distance ship stop? Looking up at the end of the sky is really heartbreaking.

The third sentence, leave the scene and fall in love. As soon as my friend set out, he thought of "where to sail at sunset", which was linked with the above sentence and naturally came. The bleak riverside contrasts sharply with the sails. The bigger the person, the bigger the person, the smaller the person. "I miss going to smoke a thousand miles". I'm really worried that the sail will come late and I can't find a place to park. This sentence expresses eager concern for friends. At the same time, guessing the whereabouts shows that people who send letters are chasing friends eastward, showing their feelings of parting. This question is really emotional.

The first three sentences are full of feelings, but there is no trace to be found, and they are always subtle. The last sentence, obviously, when a friend leaves, "the sail is far away, and the sky is exhausted." Looking at the horizon at the farewell party, I can't help but feel overwhelmed by the nothingness I turn a blind eye to. The fourth sentence, the feeling of farewell rose to a climax, called "countless tears" (Jiang Zhongshu's comment). Broken intestines points out other feelings, but it doesn't hurt the whole play. The reason is that the first three sentences have fully bred this situation, and the heart is broken, just like a reservoir opening, the flood of feelings surges out and keeps flowing. Without the preparation of the first three sentences, it is impossible to achieve such a lasting and moving effect.

The first three sentences of this poem are all in the tone of the sender, "It is as light as water, and it has a long taste", which already has the poet's self-image. The last sentence "Looking at the end of the world" is a vivid description of the sender's mode of "Although you are far away, you can still stand" (Wang Wei's "Three Farewells to the Ancestors"). What readers see here is more accurate than Meng Haoran's Poems (Wen Yiduo's miscellaneous comments on Tang poetry). The whole article uses scattered sentence patterns such as flowing clouds and flowing water, which is close to singing and full of charm, not only the writing is out of line.

This poem expresses the author's parting pain and is thought-provoking.