several thousand 和 several thousands of 的区别及具体用法

several thousand 和 several thousands of 的区别及具体用法 several thousand与 several thousands of 的用法 有没有many thousand,several thousand,和several thousands of 是several thousand还是several thousands of ? several thousand还是several thousands of several和 some的区别及用法 several thousands of与thousands of的区别 several hundred kinds of 和 several hundreds of用法及区别 thousand和thousands of的用法有什么区别? several thousands of several thousands of与thousands of有什么区别 many thousands of trees 和several hundred students的问题