"To become a referee, the Madrid Football Federation makes us take a course as well as two classes with a psychologist, because it is common knowledge that you'll be verbally abused, " he said.

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"If that becomes common knowledge here I think my job might be fairly difficult, " he said.

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And Muslims, here's something to think about: If your knowledge of Islam came from common stereotypes, wouldn't you also be misinformed about the faith and its followers?

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It is common knowledge that once a nerve suffers extreme damage, there is no coming back, be it through a broken neck, a severed back, or optical nerve impairment.

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Any way of systematising knowledge about them would thus be welcome, starting with features that the genes which cause diseases have in common.

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