But some politicians say this legacy is being challenged, amid proposals to change the 1987 Constitution to allow a parliament system of government.

VOA: standard.2009.08.03

I actually came to UCLA as a Psychology major, but I wasn't being challenged,

其实我刚上UCLA的时候主修心理学，但是觉得没挑战，

什么是认知科学？ - SpeakingMax英语口语达人

But SWAPO is being challenged by a new party,the Rally for Democracy and Progress.

VOA: standard.2009.11.27

One of the most closely watched cases involves the rights of gun owners in the city of Chicago, where the city's ban on hand guns is being challenged by 2nd amendment advocates.

VOA: standard.2009.10.01