问题补充：
two pairs of shoe加不加s,
答案：
加s If you have two shoes,its one pair of shoes.If you have four shoes,you can say two pair,or two pairs,of shoes.Both are correct.
======以下答案可供参考======
供参考答案1:
要加S 因为shoes 本身是两只（你总不能只穿一只）所以外国人都说your shoes are nice就是这个原因。还有看前面的pairs。后面是可数名次才加s或者es或其他变形。如two pieces of bread (两片面包）就是这个意思
希望楼主能理解
