So far attacks in the U.S. - at least those that are publicly known -- have been thwarted by heightened security awareness and increased counterterrorism measures from the U.S.side, as well as by both bad luck and professional incompetence on the terrorists' part.

VOA: standard.2010.05.05

In 1992, a study on literacy of United States a particular illiteracy was associated with law incompetence, with poverty, with welfare, with incarceration.

992年，一项关于美国人文化素养的研究,文化素养低下与,低下的生活水平，贫困和社会福利，以及监禁有一定关系。

麻省理工公开课 - 媒体、教育、市场课程节选