被保险人死亡后,在没有受益人或受益人先于被保险人死亡时,保险金作为被保险人的遗产。( )

The second paragraph is mainly concerned with（）.

A．how the sun evolved
B．the structure of the sun
C．why scientists study the sun
D．the distance of the sun from the planets

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如果a2=b4≠0,则a b2的值是( ).(A)1 (B)0 (C)-1 (D)1或-1 点击查看答案