A.0.20m(8″)、0.31m(12″) B.0.25m(10″)、0.31m(12″) C.0.15m(6″)、0.20m(8″) D.0.31m(12″)、0.36m(14″)
A.1.5mm B.2mm C.2.5mm
A.受力越大越好 B.剛剛受力 C.不能受力 D.鋼制螺栓的緊固力矩值