Spring is here. The weather temperatures in the north and south of my country are different between winter and summer. Swallows fly to the south to spend the winter in autumn and fly back in spring. The word "Yan Returns" comes from Yan Shu's "Huanxisha". The original poem is: A new song with new lyrics and a glass of wine, the weather is the same as last year. When does the sun set? Helplessly, the flowers fall away, and the familiar swallow returns.