Kerry said that for decades, the United States had sought cooperation from Pakistani decision makers through military aid, while paying little attention to the urgent needs of most Pakistanis.

VOA: standard.2009.05.04

Through many decades of study, biologists have teased out certain populations of cells within the bone marrow that are capable of reproducing subsets of cells.

经过数十年的研究,生物学家们在骨髓中发现了,一些细胞群,它们能够生成细胞亚群

耶鲁公开课 - 生物医学工程探索课程节选

"We have just come through what was one of the most difficult decades the middle class has ever faced a decade in which median income fell, and our economy lost about as many jobs as it gained,".

VOA: standard.2010.01.25