Often the mother had to be treated in a hospital for long periods of time.

VOA: special.2009.12.06

Cells can stop in their lifetime at some point in the cell cycle and persist for long periods of time.

细胞生命期可以停止在细胞周期的某个点,并保持很长时间

耶鲁公开课 - 生物医学工程探索课程节选

A lot of these processed foods have very long shelf lives and therefore can be stored for long periods of time.

很多加工食品为了便于储藏销售,都有很长的保质期

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

And to prepare himself, he went without sleep for long periods of time.

VOA: special.2009.03.18

Moreover, the kids we have are vulnerable for long periods of time and require our resources.

而且，我们的孩子很长一段时间,易受伤害,我们需要保护它们。

耶鲁公开课 - 心理学导论课程节选

He says even if people have a healthy body weight, sitting for long periods of time still has an unhealthy influence on blood sugar and blood fats.

VOA: special.2010.01.13