One can stop spread of disease through a community without being 100% effective in each person who gets the vaccine.

疫苗能够遏制疾病在整个社区中传播,虽然对于每个人来说它并非百分之百有效

耶鲁公开课 - 生物医学工程探索课程节选

I want to end this premise idea by talking a little bit about a person for whom, one of the chief purpose in life was to spread happiness-- Mahatma Gandhi. This is a story about him.

我想以介绍一位,一生致力于，传播快乐的人来结论这个前提-,圣雄甘地，这是关于他的一个故事。

哈佛公开课 - 幸福课课程节选