A.下端;上端螺栓 B.上端螺栓;下端螺栓 C.上端螺栓;下端 D.下端;上端
A.20±5mm B.25±5mm C.30±5mm D.35±5mm
A.25mm;40mm B.30mm;45mm C.30mm;40mm D.25mm;45mm