(someone) could sell an icebox to an Eskimo 成语
sell snow to the Eskimos|Eskimos|sell|snow
v. phr. To sell something to people who already have a large quantity of the same or similar goods.
My Alaskan friend said, "One of the hottest businesses in Alaska is refrigeration. You could say that I, as a refrigerator expert, am selling snow to the Eskimos." See: CARRY COALS TO NEWCASTLE.
(someone) could advertise an icebox to an Eskimo
Someone is an acutely smooth, charming, or actuating salesperson, such that they could advertise article to those who accept no charge or use for it. (The byword should be acclimated with caution, as the appellation "Eskimo" is advised by some to be abhorrent or derogatory. It alludes to the assorted aboriginal peoples of the commonly cold, albino arctic circumpolar regions of the globe, who appropriately would accept no acumen to buy an icebox.) I can't accept you were able to advertise an added 200 units to the hospital. You could advertise an icebox to an Eskimo!Learn more: could, Eskimo, sell