two hundred 后要不要加s啊?

two hundred 后要不要加s啊? two hundred?要不要加s? two hundred old people 的people要不要加s 为什么 two hundred hundred不用加s? The One Hundred Day Day 要不要加s的? collect stamp后要不要加s two pairs of gloves glove要不要加S? 为什么two-year-old的year不加S而two-hundred-words的word要加S 265 is two hundred and sixty-five.为什么hundred后面不用加s 3600kg用英语怎么读?three thousand,six hundred 要不要在后面加s?thousand和hu make two rooms reservation(s)要不加s 主语第三人称单数,never后动词要不要加s