1·Almost all the oxygen in water is oxygen 16, but a few molecules out of every thousand incorporate the heavier isotope 18.
水中几乎所有的氧都是氧16，但每一千个分子中就有几个含有较重的同位素18。
2·The oxygen isotope ratio of the ocean changes as a great deal of water is withdrawn from it by evaporation and is precipitated as snow to form glacial ice.
随着大量的水通过蒸发被抽离，并以雪的形式沉淀形成冰川冰，海洋中氧同位素的比率就发生了变化。
3·When the air was warm, vapor containing the heavier isotope, oxygen-18, condensed and formed precipitation, in the form of snow, more readily than did vapor containing oxygen-16.
当空气温度较高时，含有较重同位素氧-18的蒸汽比含有氧-16的蒸汽更容易凝结，并形成雪状的降水。
4·It is a global record: there is remarkably little variation in isotope ratios in sedimentary specimens taken from different continental locations.
这是一个全球性的记录：在取自不同大陆位置的沉积标本中，同位素比率的变化非常小。
5·When we count up the lithium atoms held in stars, there is only one-third as much of the lithium-7 isotope as there should be.
当我们算出了在各个恒星中锂原子的总数，同位素锂- 7的总量仅是在那里应有量的三分之一。