thousand 是单纯量词,没有复数形式,只能和具体数词连用.如:tow thousand students.不能与模糊数词连用,如:several. thousands of 是数量词组,表示“成千的”本身就包含了数量,所以不能和具体数词连用,但可以和模糊数词连用.如:hundreds of thousands of
thousand前用具体数字,后面不加of.如: five thousand books thousands of 表示”成千的”.如: thousands of books several thousand students是错误的用法.你可以说:several thousands of students