It is difficult to make oneself concentrate for long periods.

让自己长时间聚精会神是很困难的。

《牛津词典》

They can not live for long periods in cold weather.

它们不能在寒冷的天气中长时间生存。

youdao

Being lonely for long periods of time is not a great feeling.

长时间的孤独并不是一种好感觉。

youdao

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

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

Over there, it's common for children to go away for long periods in the summer.

BBC: NEWS | UK | Education | Gifted pupils ignore summer school

Spain dominated for long periods and could have been out of sight before Nilsson's late leveller.

BBC: Nilsson salvages draw for Swedes

Organizations can potentially perform well financially, socially, and environmentally for long periods of time.

FORBES: Forget Sustainability Programs