下列命题中正确的是( )
A:由五个平面围成的多面体只能是四棱锥
B:棱锥的高线可能在几何体之外
C:仅有一组对面平行的六面体是棱台
D:有一个面是多边形,其余各面是三角形的几何体是棱锥
——This history book is of great value.——Exactly. ____________ can be enjoyed from it ____________ you have a deep understanding of it, however.