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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"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.

CNN: Soccer violence: Referees under siege

Given common management it is easier to work from a common pool of resources, both financial and knowledge based.

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Everyone becomes more cautious with their money when the economy underperforms, and it is common knowledge that jobs lag behind other indicators in a recovery.

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It is common knowledge in the private sector that to foster success you experience a lot of failures.

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It is common knowledge that Deayton's journey to his present prominence has been a a slog.

BBC: Angus Deayton: Mr Urbane