Waiting in line for two hours to buy the latest iPhone is a positive reinforcement or a negative reinforcement?

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.

99 points and brainliestdiscuss two of the major causes of the increasing pollution levels in the yangtze river. make sure to include how they contribute to the water pollution

Asecular government seeks to separate its decisions and policies from influences.