Many observers say those policies have contributed to creating an impoverished, undereducated and isolated population.

VOA: standard.2009.03.26

If you have profit sharing in a firm or profit sharing in homework assignment, or any joint projects, you have to worry about too little effort being contributed because there's an externality.

如果你是一个公司的股东,或者和别人一起做作业及其他合作项目,你们需要注意到因为外部性,实际上每个人都付出了较少的努力

耶鲁公开课 - 博弈论课程节选

Other countries have contributed about 39,000 soldiers, although many are not allowed to engage in combat or serve in violent areas of the country.

VOA: standard.2009.09.03

Authorities here have acknowledged that deforestation and unregulated development were responsible for weakening the soil and contributed to the mudslides from Messina's surrounding hills and cliffs.

VOA: standard.2009.10.03

Yet,up to this day,(outside powers) have not contributed significantly to the establishment of (stability) and security, as well as economic and political development of the region."

VOA: standard.2009.05.24