几个单词单数变复数的问题catbrother classroom fun he factorykey hurse flag map （a botble of milk ）一个（piece of peper） （ a man teacher ）（an apple tree ）
问题描述：
几个单词单数变复数的问题
cat
brother classroom fun he factory
key hurse flag map （a botble of milk ）一个
（piece of peper） （ a man teacher ）
（an apple tree ）
答
cats
brothers
classrooms
funs
they
factories
keys
hurses
flags
maps
bottles of milk
pieces of paper
men teachers
apple trees