一个几何体的三视图如图所示,这个几何体应是一个( )
A:棱台
B:棱锥
C:棱柱
D:以上都不对
You never feel worried before an exam, how can you? Well, I've been working hard all the time. Surely I am _________ any exam.
下列国家与其物产之最连线正确的是( )
光斜射到平面镜上,入射光线与镜面的夹角为30°,反射角为( )