單項選擇題
A.MgO>CaO>NaF B.NaF>CaO>MgO C.CaO>MgO>NaF D.NaF>MgO>CaO
A.Fe2+ B.Zn2+ C.Pb2+ D.Ca2+
A.B>Al>Be≈Mg B.B>Be≈Al>Mg C.B≈Al D.Be>B>Al>Mg
A.四,Ⅷ B.五,VB C.三,VA D.六,ⅢB