be on one's P's and Q's 守規矩

No one has seen hide nor hair of Papaya since.  從那時起，就沒有人看到木瓜的蹤影。

mental pabulum精神食糧（書籍等）

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touch a person on the raw （比喻）觸及某人的痛處或弱點

mind one's P's and Q's 留意言行

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