讲恐龙灭绝那篇的
第十题 答案是D 我这答案都没看懂。。。。the amount of Ir in the boundary clay is too great to have from microscopic meteorites during the time the boundary clay was deposited.
我想问问 这元素这么多 从哪看出是和这陨星有联系的呢?
最后一个总结题的一个选项
The retreat of the seaways at the end of the Cretaceous has not been fully explained.
我一看就感觉不对 但是哪里不太对呢?