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Phrase(s): If you don’t see what you want, please ask (for it). [and] If you don’t see what you want, just ask (for it).
a polite phrase intended to help people get what they want. (See also If there’s anything you need, don’t hesitate to ask.) • Clerk: May I help you? Sue: I’m just looking. Clerk: If you don’t see what you want, please ask. • Clerk: I hope you enjoy your stay at our resort. If you don’t see what you want, just ask for it. Sally: Great! Thanks.
McGrawhill's American Idioms And Phrasal Verbs