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

And the basic idea was that we had some sort of a line and we knew the answer was somewhere between this point and this point.

去学习的二分搜索是有联系的,这种方法的基础思想,是我们有一个线性的序集,我们也明白答案在其中的某一段区间。

麻省理工公开课 - 计算机科学及编程导论课程节选