Birds are singing and dancing, so drunk that they won't wake up tomorrow, and spring is back.
The third sentence, "Bird Singing and Flower Dancing", uses anthropomorphic techniques to endow bird singing and flower dancing people with attributes and behaviors, vividly depicts the beautiful feelings of hearing and vision, and puts them together with drunken satrap, showing a pleasant scene of harmonious coexistence between man and nature.
The word "drunk" in the third sentence is the poetic eye, which points out the emotional commanding heights of the whole poem. The first two sentences describe concrete beauty, and the third sentence explains the degree of beauty after paving. The meaning of drunkenness is not in wine, pun intended, natural spring scenery is intoxicating, making people nostalgic and intoxicated. Beautiful scenery is often sung, and the author uses the word "drunk" to directly say that the scenery is drunk enough to make people drunk.
The fourth sentence still reflects the feeling of nostalgia, but it also extends the feeling of giving up and cherishing. After careful reading, people feel that the author wants to express his appreciation of the beautiful scenery and cherish the spring.