a set of,a piece of,a pair of的复数分别是什么

a set of,a piece of,a pair of的复数分别是什么 a pair of 与 a piece of 的区别 a pair of和a piece of的区别 英语一双,一条,等数量短语的归纳.例如a pair/piece/set/bottle.of! a set of与a pair of用法的区别 a pair of和a set of的区别 a couple of ,a piece of ,a pair of ,a bit of 的区别 a pair / a piece of 后面跟的名词是复数形式吗? a pair of glasses复数 a pair of glasses的单、复数 a pair of的复数形式 a pair of和 a piece of有什么区别