They may have a weak or damaged heart, high blood pressure or other problems of the blood system.

VOA: special.2010.07.27

It's a weak system in terms of color.

它不是基于颜色之上。

耶鲁公开课 - 文学理论导论课程节选

His research suggests that trust between people is more important in countries with a weak legal system.

VOA: special.2009.12.19