2.① The couplet "Who pities a shadow and loses a thousand clouds" means "A lone goose shadow lost in the clouds of Wan Li, which is really pitiful": the contrast between "one piece" and "a thousand weights" constitutes a great contrast and is extremely lonely; The word "who is pitiful" directly expresses feelings and embodies the poet's pity for the lonely goose. The two sentences in "Zhuan Xu" vividly describe Lu's loneliness and hard to find.
③ Tail couplet "Wild crows have no feelings and make noise all day long", which means "Wild crows have no worries and make noise all day long": The loneliness and sadness of lonely geese are set off by the carefree and lively nature of wild crows, and the tail couplet further shows the sadness of lonely geese's longing for reunion and the loyalty of struggling to find it.