单项选择题
A.0 B.1 C.2 D.1.5
A.有梯口梁,算至楼梯梁外侧边沿 B.有梯口梁,算至楼梯梁内侧边沿 C.无梯口梁,算至最上一层踏步外边沿 D.无梯口梁,算至最上一层踏步内边沿
A.2008.64 B.2000 C.1987.10 D.1978.46