After such an experience an animal often remains passive even when it can effect change—a state they called learned helplessness.

有过这样的经历后，即使是在能够带来改变的情况下，动物也常常保持被动——这种状态被他们称为习得性无助。

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Many towns often found it politic to change their allegiance.

许多城镇经常发现改变拥戴对象不失为明智之举。

《柯林斯英汉双解大词典》

From the pictures, the scientists can often say how the weather will change so that it can work better for people.

从照片中，科学家们经常可以看出天气将如何变化，以便更好地为人们服务。

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We'll talk more about this later, but it often happens that when you change your program to solve one problem you break it, and things that used to work don't work.

我们以后会更多的去讨论者一点，但是经常发生的情况是当你因为,一个问题修改你的程序的时候,你修改了程序,但原来没问题的模块。

麻省理工公开课 - 计算机科学及编程导论课程节选

Often, for a particular state change, it is easy to calculate two of these, but not the third.

对于一些特定的状态变化，它们中的两个很好计算，但是第三个往往不容易计算。

麻省理工公开课 - 热力学与动力学课程节选

Change often signals danger or opportunity and if we are especially tuned-in to change, it helps us survive ? and it helps us pass along our genes. Okay?

变化通常意味着危险和机遇,如果我们能调整适应变化，我们生存能力更强,并且能传递我们的基因，是不是？

耶鲁公开课 - 心理学导论课程节选

You can get as creative as you wish with a unique photo or graphic, and you can change it up as often as you wish.

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If anything, countries like India and China will have to expend greater effort to create a consensus regarding the need to tackle climate change, as it is often assumed, incorrectly, that growth and ecological responsibility cannot go together.

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Algeria has huge potential but the regulations change too often for it to appeal.

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