King Abdullah said he has urged the president to focus on the Israeli-Palestinian dispute, saying that is the key to resolving all the other problems in the region.

VOA: standard.2009.04.26

In a help session what he might do typically is solve between four and eight problems that illustrate the key principle being talked that week.

在帮助课程中他一般会,解决4到8个问题,来阐明那一周教的关键原理。

麻省理工公开课 - 媒体、教育、市场课程节选

The key notion of psychoanalysis is your problems are-- actually reflect deeper phenomena.

精神分析的关键假设在于,你所遇到的问题-,实际上反映出了更深层次的冲突。

耶鲁公开课 - 心理学导论课程节选