Given that you probably don't have the time it may take them to explain how that might work - or how it works now - David Cameron will tell you that he "loves the NHS", Ed Miliband that "you can't trust the Tories with the NHS" and Nick Clegg that he stopped the NHS being privatised.

BBC: Don't mention the reforms

The beauty of this theory is that subsequent calculations have shown it might explain the first and second puzzles, too.

ECONOMIST: Pulsars

Google went public in 2004, after the crash, with a warning that it might not always explain in its investment choices.

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If they were lucky, Grotzinger now thought, Gale could have the best of both worlds: a crater that might once have been habitable and a mountain that could explain why it no longer is.

NEWYORKER: The Martian Chroniclers

The next is that this variation has little to do with things you might suppose would explain it: class sizes, hours of study per subject, and spending per pupil.

ECONOMIST: Education and the wealth of nations

And they should do more to explain to Ukrainians the potential benefits of their association agreement, including the possibility that it might ultimately lead to EU membership.

ECONOMIST: Ukraine and Europe

Be sure to keep in mind that potential investors might not be as familiar with your industry so you have to clearly explain your concept and where it fits in.

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