下列物质中,含有极性共价键的离子化合物是( )
A.NaOH
B.H2
C.H2S
D.CaCl2
答案:A
People have realized that they should go on __ balanced diet and do _____ exercise every day.
A.a; /
B.the; an
C.the; the
D./; an
论述运用马克思主义(恩格斯)国家起源理论评价非马克思主义关于国家起源的主要观点?