Master and disciples pressed on through the bitter cold, sleeping in the rain and dining on the wind.

宿雨餐風 sù yǔ cān fēng — to lodge in rain and make a meal of wind — is the set phrase for hard travelling, and it is still the one Chinese reaches for. 宿 is sù, to spend the night.

As they went, another walled city came into view.

正行間 zhèng xíng jiān is "right in the middle of walking" — the novel's usual way of interrupting a journey. Nine characters, and the plot restarts.

Tripitaka asked, "Wukong, what place is that over there?"

那廂 nà xiāng is "that quarter," pointing rather than asking which — so 那 is nà and not the questioning nǎ.

Pilgrim said, "You will know when we get there.

Wukong at his most laconic. The joke is that he does not know either, and says so in a way that sounds like knowledge.

If it is the seat of a western king, we must have our travel rescript certified; if it is only a prefecture or a district, we go straight through."

The bureaucratic reflex, and it is the engine of half the novel's plots. 倒換 dào huàn — with 倒 read dào — is to exchange one document for another: at each kingdom the rescript is stamped afresh, rather like getting a visa endorsed at every border. The two clauses are built on the same frame, 若是 — if it is — which is why they are set here as a single sentence.