Plus the cliff edge is constantly moving and it's dangerous to have a path running along it.

BBC: Two steps forward, one back

And of course economic and technological limits are constantly moving things.

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The manner in which sails are designed to capture wind meanwhile ensures that any design, painting or print is constantly moving and changing shape when on the water, altering the appearance of the artwork in the process.

CNN: , for

The Arctic sea ice is constantly moving, breaking open and reforming into different shapes - which means we can end up moving several kilometres in any direction while we are asleep in our tents.

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If there is one thing we know for sure, we will continue to have no idea of where Governor Romney really stands on both domestic and foreign issues because where he stands is a constantly moving target.

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With doctors constantly re-locating and departments lending, sharing, and moving some of these (approximately 10, 000) devices around, the need for a robust tracking system is critical.

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Traders at Citi and elsewhere are "pricegivers"--in seeking trading profits, they are constantly moving capital to what the markets see as its highest use.

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He is intelligent enough to divert us from the darker bits with, among other things, a phenomenal, constantly moving set, designed by Bob Crowley (who also took charge of the costumes): scrims and sets fly miraculously into the rafters, only to be replaced by others whenever Poppins has a change of mood.

NEWYORKER: Mary Poppins