She says one slum in Nairobi,Mathari,has only about three public primary schools nearby.

VOA: special.2009.08.24

This Cambridge History of Food talks about three separate primary phases in human food evolution: one beginning a million and a half years ago, another about 700,000 years ago, and then the 10,000 year ago one that I talked about just a moment ago.

剑桥饮食史》描述了,人类饮食结构演化过程中的三个不同阶段,其一,始于一百五十万年前,其二,距今约七十万年,其三,距今一万年,我们刚讨论过了

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

At the week-long conference, participants are focusing on three primary roadblocks to getting and keeping girls in school: violence,poverty and the poor quality of education being offered.

VOA: standard.2010.05.19