Paragraph 3
A.Competing Explanations
B.Unknown Attacks
C.Mysterious Explosion
D.Star War
E.Importance of Finding Evidence
F.Explanation that Worries Scientists
正确答案是F
Paragraph 3
A.Competing Explanations
B.Unknown Attacks
C.Mysterious Explosion
D.Star War
E.Importance of Finding Evidence
F.Explanation that Worries Scientists
正确答案是F