Does it need refinement in some way?" "And if it does need some adjustment in light of the events that have taken place over the last number of months, including the election and so on, and then what are the implications of that in terms of General McChrystal's resource request?" The secretary said the United States will not abandon its core mission in Afghanistan, which President Obama described as the destruction of the al-Qaida terrorist network, because it is "critical" to U.S.national security.

VOA: standard.2009.10.23

So let's do a quick clicker question, and you tell me how many valence electrons does fluorine have? Remember, valence electrons are different from core, they're only the outer-most electrons in the outer-most shell.

那么让我们来做一个小选择题，请大家来告诉我,氟有多少个价电子，要记得，价电子与芯电子不同，它们是在最外壳层的最靠外面的电子。

麻省理工公开课 - 化学原理课程节选

We do have, um, a focus on non- Western cultures in one of our core curriculum classes.

在核心课程中，我们确实有一门课不是讲西方文化的。

哥伦比亚大学的教程 - SpeakingMax英语口语达人

The other threat is eonomic, and all the economic issues are tied in my judgement, to the same core problem which is the long-term fiscal challenge that this country faces.

另一个威胁是经济方面的，我认为所有的经济问题,都和一个核心的问题分不开,就是我们国家面临的,长期财政挑战。

普林斯顿公开课 - 国际座谈会课程节选