来自《耶鲁大学开放课程：生物医学工程探索 第9集 第9集》

• 
  
  Eventually you develop a scab, as it healed,
  愈合之后会变成一个疤
• 
  
  and then it would--and then the scab would fall off,
  这个疤后来会脱落
• 
  
  and you'd be left with a scar.
  你身上会留下疤痕
• 
  
  But what if instead of taking the fluid from a cow,
  但假如不从奶牛那儿取得脓液
• 
  
  I inoculated--he inoculated me, let's say,
  假设说是从他那里接种
• 
  
  and waited until I had the lesion at the right stage,
  等到病变程度合适
• 
  
  then took some of my fluid and gave it to
  然后把我的脓液给
• 
  
  Brian and Nate and Mirtalla
  布莱恩和纳特还有米特拉
• 
  
  and spread it through the community around me.
  并在我身边的人们之间传播
• 
  
  Now we don't need the cow anymore
  由于它可以在人与人之间传播
• 
  
  because you could pass it from one person to another,
  就不再需要奶牛了
• 
  
  and pass the immunity from one person to another.
  就可以把免疫力在人与人之间传播