A:4
B:3
C:2
D:1
如图,在半径为10cm的圆中作一个正六边形ABCDEF,试求此正六边形的面积.
-________ do you think of your school life?
-It's very exciting (令人兴奋的).
下图示意某地地质剖面,回答下列各题。