thousand前加several或者many时其后要加s吗?

thousand前加several或者many时其后要加s吗? several ______(thousand) dollars thousand要加s吗?several不是加可数名词的复数吗? 又一道英语数词练习题例题he has ()books in his studyA several thousands B some thousands of C some thousands Dsome thousand of在本章开头作者说thousand前加数词或several many不用加s而且也不接of的（后面是代词宾格 ____foreigners come to visit this museum every year填several thousand of还是several thousand为什么 还有如果是five thousands 呢要不要加of many much several到底有没有several thousand 或者several thousands ofmany thousand或者many thousands ofsome thousand或者some thousands of说什么的都有我都晕了啊但是两个中考书可不是这么说的好像 Many ____ trees shoul “several thousand students ”中的“thousand为什么不是复数? several thousand与 several thousands of 的用法 英文中的千,百thousand和hundred前加数字时末尾加不加s several thousand 和 several thousands of 的区别及具体用法还有这一题：There are_____students in my school A.several thousand B.several thousands of hundred, thousand, million等词前面与具体数字/several和不具体数字修饰时的不同情况.hundred, thousand, million等词前面有具体数字或several修饰时,不加-s,不与of 连接,如是many等不具体数字就加-s,与of 连 是several thousand还是several thousands of ?RT这两种我都见过。。 several times前面加介词for吗?two times呢?那two times前必须加介词for吗？ thousand要加s吗 thousand用法 何时加S! several 的用法several与hundred,thousand,million在一起怎样使用啊,hundred,thousand,million 是用单数还是复数?如果hundred,thousand,million后有名词呢? China has a population of a thousand million.我想请问一下这句population 前为什么还要加个a hundred前如是具体数字不加S 不加OF,如果不是具体的 就加S加OF some,many,several算不算具体数字 two thousand of为什么thousand不加s