Few doubt his mastery of the facts, so this doesn't mean prepping him on Afghan geography or drilling into the detail of marginal tax rates.

BBC: Obama's do-or-die debate

So if you choose to have Shepard learn Combat Mastery, you can assign him particular benefits of that power depending on whether you wish to emphasize stealth, or player damage, or team damage, etc.

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"Indeed in our view such competence is central to the success of primary mathematics, so much so that we would recommend an earlier emphasis for the mastery of some basic skills such as multiplication tables, " he said in a paper due to be published later this week.

BBC: Primary maths plan threatens 'too much too soon'

The waltz is sacred to Viennese high society, and rules are so strict that if you want to take part in any of the exclusive opening balls, a mastery of the Viennese waltz reverse turn (which for non-dance folk means, basically, to the left) is required by all ball committees.

BBC: Finding your rhythm in Vienna