题目内容:
Theword“period”inParagraph3meansthelengthoftime
A.overwhichstarvaryinbrightness B.forwhichEtacarinae’sbrighteninglast
C.Etacarinaetakestobecomeasupernov
D.ittakesthelaserfromEtacarinaetotraveltotheeart
参考答案:
答案解析: