hat为什么加s

hat意思是帽子，加s的意思是复数情况，例如：

1.The hats are made in three sizes: small, medium and large.这些帽子分小、中、大三个尺码。

2.The children were busy cutting and pasting paper hats.孩子们忙着剪裁和粘贴纸帽子。

3.I'm wearing two hats tonight ─ parent and teacher.我今晚身兼两职——既是家长又是老师。