题目选项分析

To popularize the asteroid theory of dinosaur extinction, paleontologists

have to provide somewhat stronger evidence than now linking

the disappearance of fossil records and the layer of sediment in the Earth's crust caused by an asteroid impact.

To popularize the asteroid theory of dinosaur extinction, paleontologists

would have to provide somewhat stronger evidence than they do now linking

the disappearance of fossil records and the layer of sediment in the Earth's crust caused by an asteroid impact.

题目基本信息

难度：难