Nevertheless, even in those earliest days, it is absolutely impossible to do it all and certain functions will need to be delegated.

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"Under-13s create a real problem because it is absolutely impossible in the current set of standards to be sure about the age of anyone because children will lie, " he said.

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Furthermore, it is, as argued by Alan Greenspan recently, absolutely impossible for the US to be forced to default on their debt.

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Criminologist Prof David Wilson of Birmingham City University, who once worked on the sex offender treatment programme at Grendon prison, says psychological profiling can indicate whether such a criminal is less likely to re-offend - but ultimately, the nature of the offence makes it impossible to be absolutely certain.

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