"Any discussion of settlements, any discussion of the issues of living in East Jerusalem, should not take precedent over the primary focus of import which is the growing threat of a nuclear Iran,"

VOA: standard.2009.08.06

It's more obvious because there are probably fewer lines there, so that you can focus on the primary line, the basic line--the bass line.

更明显的是这里也许有几条线，所以你可以将重点放在主线上，基准线，也就是低音线。

耶鲁公开课 - 聆听音乐课程节选