hundred/thousand/million 的数

题目

hundred/thousand/million 的数
我以前学过:hundred/thousand 前面加基数词时不用复数形式.( two hundred )
当它们后面接of 短语时要用复数( thousands of people)
但是我又看到了 :Many millions are trying to do so.( 教科书)
Several hundred in the city have lost their houses.(词典)
2者都是代词时为什么一下词尾＋s ,一下又不加．
此外：hundred/thousand 前面加基数词时词尾不是不加s
为什么下面的句子要加s
The state invested two millions .国家投资200万元．

答案

one hundred- no S because it is not a pluralTwo hundreds- why because two is more than onebut!twenty thousand poundS is correct...because you have poundsTwenthy thousands pound is wronggenerally speak...