A.CuSO4 B.AgNO3 C.KOH D.H2SO4 E.NaCl F.Na2SO4
通电一段时间切断电源,请填写下列空白.
You will achieve nothing ______ you work hard in a proper way.
- Would you like some for dinner?
- OK.
从海陆分布角度来看,我国属于( )
实验室里常常用验电器来检验物体是否带电.用被丝绸摩擦过的玻璃棒接触验电器的金
属球,可发现验电器的两片金属箔会因排斥而张开,对这一现象理解正确的是( )