In its 40th year, Earth Day is intended to bring awareness about what people can do in their everyday lives to contribute to a cleaner more sustainable planet.

VOA: standard.2010.04.25

Because when you do favor to people, people are more likely to contribute to your campaigns.

当你为群众谋福时，人们更有可能,为你选举加油。

斯坦福公开课 - 经济学课程节选

If I'm happier, I'm more likely to contribute to other people's happiness and wellbeing.

如果我更快乐，我更有可能,对他人的快乐和幸福作出贡献。

哈佛公开课 - 幸福课课程节选