Twenty-eight percent of this group had income levels that were below the poverty line.

VOA: special.2011.03.11

At some point, maybe a week later, four to eight days later, you would start to see antibody levels rise.

之后,或许一周之后,四天到八天之间,就可以看到抗体的浓度开始上升

耶鲁公开课 - 生物医学工程探索课程节选

So if on each iteration of merging I'm doing eight things or more generally, N. That then begs the question, how many levels of this tree are there actually?

可见对于合并我需要迭代8次,一般情况下是N，这取决于具体问题，那么在这棵树中一共有多少层呢？

哈佛公开课 - 计算机科学课程节选

Carbon monoxide levels in the blood return to normal after eight hours.

VOA: special.2010.03.09