单选题A double star is a star that（）.Ahas a declination equal to twice that of the SunBcomprises two stars that appear close togetherCis twice as bright as a single starDsuddenly becomes much brighter and then fades
单选题
A double star is a star that（）.
A
has a declination equal to twice that of the Sun
B
comprises two stars that appear close together
C
is twice as bright as a single star
D
suddenly becomes much brighter and then fades
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