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1·The problem is that a supernova blast pretty much eradicates all evidence of what the progenitor star was.

问题是超新星爆发会把它的前身天体资料几乎全部抹掉。

2·The deciding factors for whether a core collapse produces a GRB appear to be the mass and rotation rate of the progenitor star at the time of its death.

核心坍塌是否能产生GRB的关键因素，似乎在于原来恒星临终时的质量与转动速率。