hundred的各种形式用法

具体数字用法（也就是基数词,此时是hundred是不能加s的）,后面必须接名词复数：

如：a hundred books; two hundred books; three hundred books;

非具体数字用法（也就是名词,此时hundred常写成hundreds of）,后面也是接名词复数.

hundreds of students; many hundreds of students; several hundreds of students;