The last time the United States Education Department asked young people how long they took to finish college was in two thousand one.

VOA: special.2009.07.23

There were a few things I didn't get to finish last time in talking about particularly gene transfer in mammals.

我们还有一些上次未完成的内容要讲,尤其是哺乳动物的基因导入

耶鲁公开课 - 生物医学工程探索课程节选