右手蓋住 Covered With His Right Hand
我和你換換。我和你換換。」三藏聞言道：「悟空，這仙長實乃愛客之意，你吃了罷，換怎的？」行者無奈，將左手接了，右手蓋住，看著他們。我和你换换。我和你换换。」三藏闻言道：「悟空，这仙长实乃爱客之意，你吃了罢，换怎的？」行者无奈，将左手接了，右手盖住，看着他们。
逐句解 Line by line
"Let me swap with you. Let me swap with you."
Said twice, and the doubling is not decoration. These are the second and third times Pilgrim has asked to exchange cups, and he has stopped bothering to dress it up. In a chapter that has used doubled speech for urgency four times already — 師兄，師兄, 謹言，謹言, 不用打，不用打, 恕罪，恕罪 — this is the one where the speaker is being deliberately, visibly insistent.
Tripitaka heard this and said, "Wukong, the immortal gentleman means it kindly to his guests. Drink it, and have done. What is there to change?"
And there it is. 悟空 — Wukong, Awakened to Emptiness — is Pilgrim's religious name, and his master uses it here to overrule him. 愛客之意, a kindly feeling towards guests, is Tripitaka repeating the host's own account of himself back as fact. 換怎的 — what is there to change — is four characters of impatience.
Pilgrim, having no choice, took the cup in his left hand, covered it with his right, and watched them.
無奈 is to have no alternative — overruled, not persuaded. Then three small physical actions that tell you everything: left hand takes, right hand covers, eyes go to the others. 蓋住, covering it over, means nothing is going into that cup and nothing is coming out of it. And 看著他們 takes 著 as zhe, the durative: he did not glance at them, he went on watching them.
Pilgrim is overruled by his master and this is the whole tragedy of their relationship in three sentences. He has seen the anomaly, tested it, been given a smooth answer, and pressed anyway — three times. And Tripitaka, who cannot see any of it, tells him to stop being rude to their host.
It is worth being fair to Tripitaka here, because the book usually is not. From where he sits, his disciple is badgering a poor country priest about which cup he gets, having already been told the reason twice. Insisting further would be grotesque. He is being a good guest, and being a good guest is the thing that has nearly killed him in every chapter of this book.
The last sentence is the one to keep. Left hand takes, right hand covers, and 看著他們 — he went on watching them. He does not drink and he does not argue. He holds a sealed cup and observes, which is the most Pilgrim thing imaginable, and it is why in the passages ahead three men will be lying on the floor and one will not.