题目选项分析

New theories propose that catastrophic impacts of asteroids and comets may have caused reversals in the Earth's magnetic field, the onset of ice ages, splitting apart continents 80 million years ago, and great volcanic eruptions.

New theories propose that catastrophic impacts of asteroids and comets may have caused reversals in the Earth's magnetic field, the onset of ice ages, the splitting apart of continents 80 million years ago, and great volcanic eruptions.