A.△ρ=ρ標+△ρ修-ρ被 B.△ρ=ρ標-△ρ修-ρ被 C.△ρ=ρ標+△ρ修+ρ被 D.△ρ=ρ標-△ρ修+ρ被
A.25 B.10 C.20 D.0
A.游標卡尺、鋼板尺 B.米尺、游標卡尺 C.玻璃偏光應力儀,鋼板尺 D.玻璃偏光應力儀,游標卡尺