问题详情

According to the professor, how do geologists interpret the presence of erratics in the tropics？

A．It indicates that carbon-dioxide levels were once higher there.

B．It is evidence of global glaciation.

C．It indicates that the Earth may cool off at some point in the future.

D．It is evidence that some glaciers originated there.

此题为多项选择题。请帮忙给出正确答案和分析，谢谢！