In addition,using the lambs costs much less than hiring workers to prune the vines for seven weeks in the summer.

VOA: special.2009.07.14

Realize that there's this wonderful mechanism in place that allows you to put your toe in the water for several weeks no less and then get a sense, and then decide whether or not this is something for you.

要知道这种好的评分体制哈佛也有,在这种机制下你可以先试听几周,熟悉这一机制，然后再决定这是否适合你。

哈佛公开课 - 计算机科学课程节选

And they were less likely to have a stillbirth, the loss of a fetus after twenty weeks.

VOA: special.2010.08.11