白鶴丹鳳 White Crane And Vermilion Phoenix
行者又變作一個烏鳳，專一趕黃鷹。牛王識得，又變作一隻白鶴，長唳一聲，向南飛去。行者立定，抖抖翎毛，又變作一隻丹鳳，高鳴一聲。行者又变作一个乌凤，专一赶黄鹰。牛王识得，又变作一只白鹤，长唳一声，向南飞去。行者立定，抖抖翎毛，又变作一只丹凤，高鸣一声。
逐句解 Line by line
Pilgrim changed again into a black phoenix, bent solely on driving the yellow hawk.
專一 is a word in its own right, meaning single-mindedly, so 一 holds at yī and the ordinary tone rule that would lower it before the dipping tone of 趕 has to be overridden. It is the third such site in the chapter, after 一則 twice.
The Bull King knew it, and changed into a white crane, gave one long cry and flew away southward.
The white crane is the first shape in the chase chosen for distance rather than for fighting: one long cry and away to the south. 長唳 takes 長 at cháng, long, against the zhǎng the bare character would otherwise give, and 唳 is the particular word for the cry of a crane. 識得 takes 得 at dé.
Pilgrim steadied himself, shook out his flight feathers, and changed into a vermilion phoenix, giving one high call.
The vermilion phoenix is a claim of rank rather than of strength: what follows will turn on precedence among birds and not on talons. 翎毛 are the stiff flight feathers as against down.
The chase moves up the order of birds. Hawk answers falcon, black phoenix answers hawk, and then the Bull King stops trying to win the exchange and takes the white crane, which is chosen for distance rather than for fighting: one long cry and away to the south.
The Great Sage answers with the vermilion phoenix, and the answer is not about talons. It is a claim of precedence, and the next passage will settle the exchange on precedence alone. For three transformations the contest has been a matter of which bird eats which; here it becomes a matter of rank.