...army city story baby butterfly country m toy piay day key boy...答:为你解答-名词单数变复数。family-families,家庭 country-countries,国家 army-armies,军队 city-cities,城市 story-stories,故事 baby-babies,婴儿 butterfly-butterflies,蝴蝶 country-countries,国家 toy-toys,玩具 play-plyays,戏剧 day-days,白天 key-keys,钥匙 boy-boys,男孩 ...