According to some historians, when did the middle ages begin?And when id this era end?

AD 476 beginning. ending 1500

Explanation:

it began with the fall of the roman empire

disequilibrium means that either supply is greater than the demand for an available good, or that the demand for a product outstrips the available supply. it implies that the price for a is either too low creating large demand, or too high creating a large surplus of supply.

- "it was a failure that was an embarrassment for the kennedy administration."

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