He says the process of sorting through those areas, which include sites around the country,but concentrated in the mountainous northern areas, will be a long and difficult one, though it is work that needs to be done in the name of the victims' families.

VOA: standard.2009.12.18

I'm going to say, quite to the contrary, the positive charge is concentrated at the center in a tiny, tiny, tiny volume.

我要说的是，完全相反，正电荷集中在中心,在一个非常非常小的体积内。

麻省理工公开课 - 固态化学导论课程节选

They're red because they contain a special protein called hemoglobin which is very concentrated inside the cell.

红细胞的红色源于,其内部一种叫做血红蛋白的特殊蛋白质,血红蛋白在细胞内的浓度很高

耶鲁公开课 - 生物医学工程探索课程节选