题目内容：

over ( )years ago, there were no humans here. 用two million还是millions of,为什么?
over ( )years ago, there were no humans here.
用two million还是millions of,为什么?

优质解答

over (two million) years ago, there were no humans here.
因为前面用了over,后面就一定用具体的数字
如果没有over,就要说millions of years ago