og10第九篇的疑問

YLC1000

 When an ice age begins, the continental ice sheets grow, steadily reducing the amount of water evaporated from the ocean that will eventually return to it. Because heavier isotopes tend to be left behind when water evaporates from the ocean surfaces, the remaining ocean water becomes progressively enriched in oxygen 18.

1.想請問一下ocean後面那個that是形容前面哪一個名詞，句子的結構是什麼

2.這一段話是不是說當冰河時期開始時，海水的蒸發變少了，而海水蒸發時oxygen 18這比較重的成分會留在海哩，已致於海水中oxygen 18的比率較高

  那是不是可以推出冰河時期→蒸發減少→比較少的oxygen 16被蒸發→海水中oxygen 18的比率降低   

小弟這樣的推論有問題嗎 ，為何跟這段句子最後一句話不符

The higher the ratio of oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down.

請各位高手幫個忙

The higher the ratio of oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down.

請各位高手幫個忙

phoenixfr

应该是这样的.

河時期開始時，蒸發后返回海洋的海水變少了，而海水蒸發時oxygen 18這比較重的同位素會留在海哩，已致於海水中oxygen 18的比率較高

jason_jufe

以下是引用YLC1000在2007-3-1 16:09:00的发言：

 When an ice age begins, the continental ice sheets grow, steadily reducing the amount of water evaporated from the ocean that will eventually return to it. Because heavier isotopes tend to be left behind when water evaporates from the ocean surfaces, the remaining ocean water becomes progressively enriched in oxygen 18.

1.想請問一下ocean後面那個that是形容前面哪一個名詞，句子的結構是什麼

2.這一段話是不是說當冰河時期開始時，海水的蒸發變少了，而海水蒸發時oxygen 18這比較重的成分會留在海哩，已致於海水中oxygen 18的比率較高

  那是不是可以推出冰河時期→蒸發減少→比較少的oxygen 16被蒸發→海水中oxygen 18的比率降低   

当冰河时期开始，陆地大冰原开始增长，同时减少了海水蒸发的水量，这些水将回到海里。（that指代 water)

蒸发减少不能推出氧16被蒸发的少。这里有问题，不是题目直接得出的推论。

蒸发减少－－海水重氧18增加（前提是重的元素比较容易留下）