What are the legislative tools of persuasion?

What river valley civilization in the plow

If a swimmer is traveling at a constant speed of 0.85 m/s,how long would it take to swim the length of a 50m olympic sized pool?

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.