Infertility is a public health problem that affects all societies, not least traditional ones such as the Maasai of east Africa.

不孕症是个公共卫生问题，影响到所有社会，尤其是传统的社会群落，如东非的马赛部族。

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But if I give them all really hard problems, they don't get the chance to develop the good problem-solving habits that they'll get with the easy ones.

但是，如果我给他们的都是非常难的问题，那么他们就没有机会来养成良好的解决问题的习惯。

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The problem affects metropolitan areas of all sizes, but big ones-the country's economic engines-are in the worst shape.

大中小型城市皆受此问题困扰，但尤以作为国家经济引擎的大型城市为甚。

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