通过测量一束头发上较重的氢和氧同位素的比例，科学家可以构建一个地理时间轴。

By measuring the proportion of heavier hydrogen and oxygen isotopes along a strand of hair, scientists can construct a geographic timeline.

youdao

科学家称这种标志物为“替代品”，代表他们真正想要测量的东西——在本例中，即在过去冰的地理范围。

Scientists call such markers "proxies" for the thing they actually want to measure — in this case, the geographic extent of the ice in the past.

youdao

参考国家地理月球测量结果。

Take National Geographic's moon quiz.

youdao