A.維氏硬度50 B.布氏硬度50 C.洛氏硬度C標(biāo)尺50 D.洛氏硬度R標(biāo)尺50
A.2-8SB.10-15SC.30±2SD.60S
A.能量守恒 B.動(dòng)量守恒 C.光電效應(yīng) D.動(dòng)能守恒