Мы в Telegram на канале Учим Английский
once in a blue moon
once in a blue moon {adv. phr.}
Очень редко; практически никогда.
Coin collecting is interesting, but you find a valuable coin only once in a blue moon.
Once in a blue moon someone grows a very pale marigold, but no truly white marigolds have been raised.
Ср.
Категории:
Источник: A Dictionary of American Idioms
