Задание №82166 ЕГЭ Английскому языку

 Образуйте от слова SWIM однокоренное слово так, чтобы оно грамматически и лексически соответствовало содержанию текста.

Do you know that penguins are considered to be birds. though they cannot fly? That’s why they are often referred to as “flightless birds”. Penguins are the best ____________ in the bird world. They spend most of their lives in water, where they catch fish and tiny animals called krill.