来自《耶鲁大学开放课程：新生有机化学 第1集 第1集》

• 
  
  and three-quarters of the other,
  另一种占四分之三
• 
  
  and the average is thirty-five and a half;
  平均值为三十五点五
• 
  
  thirty-five and thirty-seven.
  三十五和三十七按比例平均
• 
  
  But in fact it depends on where you get chlorine from,
  事实上 取决于你从何处取得氯
• 
  
  what the ratio is.
  同位素的比例为多少
• 
  
  There's thirty-five and a half for a standard atomic weight,
  三十五点五是标准原子量
• 
  
  but it ranges quite a bit,
  但它的范围相当大
• 
  
  depending on where you get it.
  取决于你从何处取得氯元素
• 
  
  So by measuring these ratios,
  因此 测量这些比例
• 
  
  which is a lot like these odds in the betting,
  很像是计算赌博的赔率
• 
  
  you can tell where things came from.
  你可以藉此得知这东西来自何处
• 
  
  You can tell where hydrocarbons came from sometimes that way.
  有时也可以这种方式得知碳氢化合物来源