With only one observation per country, it is impossible to control for unobserved heterogeneity across countries.
由于每个国家只有一个观测结果，因此不可能控制各国间未观察到的异质性。
However, he conceded that it's impossible to control everything.
尽管如此，他承认控制一切是不可能的。
Only the brave sell at auction, for it is impossible to control who buys or what price they will pay.
只有胆大的人才敢在拍卖行交易，因为在交易会上几乎是无法控制谁会去购买，或是他们要付多少钱。
It's almost impossible to control how people use social media.
要控制人们如何使用社交媒体几乎是不可能的。
Office workers tried to put out the fire, but it was impossible to control it.
办公室的工作人员试图把火扑灭，但是他们控制不了火势。
Office workers tried to put out the fire, but it was impossible to control it.
办公室的工作人员试图把火扑灭，但是他们控制不了火势。
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