GRE Reading Comprehension: Maggoosh-GRE阅读Maggoosh - K4X042T05Z3IBL78M

The Alvarezes concluded that a meteorite was responsible for a mass extinction because A. dinosaurs were prone to the effects of iridium B. it could account for the heightened presence of an element C. cosmic dust in the form of iridium constantly makes its way to the Earth's surface D. the scaglia rossa had a sudden gap in traceable iridium E. the scientific community was unable to provide a more valid hypothesis