Charles Darwin developed the theory of how living things develop from simpler organisms over long periods of time.

VOA: special.2009.02.25

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

So war time periods were typically periods of great inflation and debasement of the currency.

所以，战争时期通常是,严重的通货膨胀,和货币改造的时期。

耶鲁公开课 - 金融市场课程节选

The two time periods tested whether people were more likely to act differently in the short term than in the long term.

VOA: special.2009.03.03

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

The next time you think about going without sleep, consider this: Laboratory animals that are kept awake for long periods of time ...die.

VOA: special.2009.08.26

When these tyrannies take place, they last for different periods of time, but when the tyrant is removed, what follows after that is, there is never again in that town a one-man rule of any kind.

当僭主统治步入历史舞台,它走过了很多历史时期,但当它寿终正寝之后,在那座城邦里再也没有出现过,任何形式的独裁者了

耶鲁公开课 - 古希腊历史简介课程节选

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

VOA: special.2009.12.06

Over long periods of time, these small changes result in the creation of new species.

VOA: special.2009.12.01

He thought that this was evidence that the bottom of the ocean had been lifted up by powerful geological forces over long periods of time.

VOA: special.2009.02.25

Astronauts worked for longer periods of time in the hostile environment of space.

VOA: special.2009.07.01

The interrogators were told they could put them in painful standing positions, deprive them of solid food, keep them awake for extended periods of time, lock them in cold rooms, and submit them to the technique of simulated drowning known as waterboarding.

VOA: standard.2009.04.17