If you or I buy it, it costs $51 per dose, you need three doses to be effective.

如果你或者我购买它,每支将花费五十一美元,你需要购买三支才会起效

耶鲁公开课 - 生物医学工程探索课程节选

Now, the polio vaccine that Salk produced was very effective, but it required a fairly large dose of the vaccine and it had to be injected into the arms of children.

索尔克生产的小儿麻痹症疫苗效果显著,但是,该疫苗的单支注射剂量非常大,而且必须通过小孩的手臂进行注射

耶鲁公开课 - 生物医学工程探索课程节选