单选题
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
【正确答案】
B
【答案解析】
[解析]从文章第二段首句：Solar astronomers do know that the sun is divided into five layers or zones．得知。故本题答案为B。
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