When was the beginning of the canal era? the invention of steamboats the building of the erie canal shortly after the industrial revolution

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What refers to the existence of more than one level of government in the country

Which statement is a good description of a model? a) models are a description of nature based only on one or two variables. b) models are testable ideas but they are not very to most people. c) models are a description of nature that predicts more accurately than real events. d) models are an approximiation of a real system that omits all but most essential variables in a system.

Which of the following policies is an example of a command-and-control policy? a. subsidies to education b. maximum levels of pollution that factories may emit c. tradable pollution permits d. none of the above is an example of a command-and-control policy.