A.橫軸垂直于豎軸 B.視準(zhǔn)軸垂直于橫軸 C.水準(zhǔn)管軸垂直于豎軸 D.視準(zhǔn)軸垂直于豎軸
A.8″ B.9″ C.13″ D.24″
A.45° B.90° C.180° D.270°