单项选择题
A.NH3 B.N2H4 C.N2H62+ D.N2H5OH
A.3F1D B.1D3D C.2P3P D.1S2P
A.n2 B.2(l+1) C.n-1 D.n-l-1
A.K B.Rb C.Cs D.Na
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