So, how we eradicated smallpox was -- max vaccination wouldn't work. You could vaccinate everybody in India, but one year later there'd be 21 million new babies, which was then the population of Canada.
那我们是怎么根除了天花的呢？要大范围的接种是不可能的 即使今年给全印度的人注射了疫苗，但是下一年马上又有 两千一百万新生婴孩 这相当于加拿大的人口