问题补充:
We all know that dinosaurs lived on the Earth more than years ago.
A. sixty million
B. millions of
C. sixty million of
D. million of
答案:
(答案→)A. sixty million
B. millions of
C. sixty million of
D. million of
解析:句意:我们都知道恐龙在地球上生存在6千万年前。表示确切数字,million不用复数;表示概数,million必须用复数,并且和介词of连用,所以选A。