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俼иxҪcęC

l(f)rg:2017-06-29݋f

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ęCһ俼(jng)ҪWYx{(dio)

F(xin)ڸW(wng)վx俼(jng)ͼкܶ@Щ(ni)݌҂Ă俼ЎǴҪWYxҪһEҪW(j)ԼČHrM{(dio){(dio)֮ǰһҪM֪Լˮƽ~RZwϵLyֻг˽ԼĆ}cᘌԵĽb俼(jng)򞣬ԼĂ俼|(zh)

ęC俼YJTPO

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ęC}һԭĞ(j)

иx}Уһ֌Wǐ뮔ȻԼ˼SʽMx@xĴ𰸺ܶr¶e`Сһһ}Ŀ

According to paragraph 4, what aspect of extinction episodes does the companion-star hypothesis supposedly clarify?

A. Their location

B. Their frequency

C. Their duration

D. Their severity

companion star hypothesisP(gun)I~λһThe possibility that mass extinctions may recur periodically has given rise to such hypotheses as that of a companion star with a long-period orbit deflecting other bodies from their normal orbits, making some of them fall to Earth as meteors and causing widespread devastation upon impact.fmass extinctionķͰl(f)֧companion star hypothesis@hypothesisf܉׃ΌһЩwƫx܉ɞEǵԭfҴΰl(f)܉extinctionlʣB}һҪԭĞ}ȡиx߷

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