For those equilibria do not exist, they are constantly undermined and challenged by changes in technology.

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Even though his patience and sanity are constantly being challenged well beyond the normal limits, Brian Cashman needs the Yankees as much as they need him.

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Dr. Martin Luther King, Jr. inspired a nation and challenged future generations to constantly strive for a more perfect union.

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Because what you think you know needs to be constantly challenged by the latest and greatest way to potentially think about things.

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