These formulas operate on extensive databases of numbers
that define the objects in the pictures as they exist in mathematical space.
全句是什么意思呢?根据我的理解,这里的they就是代指objects才对么
4,应该是B吧?第一段的最后一句很长的话,they realized that if the various rock unites could be dated by ... age, correlations among ... rocks....could be ...established...
我找不到哪里说了D