"She worked really hard while she was in high school to go to college.

VOA: standard.2009.12.04

Altruism" is the biologists' term meaning kindness,generosity, and evolutionary biologists have worked really hard to explain why animals might evolve to be kind.

利他主义是生物学术语,意思是善良，慷慨，进化生物学家努力去解释,为什么动物进化趋向善良。

耶鲁公开课 - 心理学导论课程节选