关于hundred的用法?
有两个题：
_____people are sitting quitely in the hall and listeing to the speech.
A. Six hundred of;B. Six hundreds; C. Six hundred; D. Six hundreds of
So far, they have sold over three_____books.
A. million;B. millions of;C. million of;D. millions;
正确答案,是D.和A.
我有点看不明白,我倾向于C和A.请高手们帮我看一下,是我错了还是答案有问题.多谢了!