Which item would be considered a secondary source on world war

Answer quickly! correct answers only! how did an agricultural surplus relate to expanded trade during the high middle ages? a)trade increased because surplus crops could be traded. b)trade decreased because surplus crops were needed to feed local populations. c)trade decreased because surplus crops led to an oversupply of grains that could not be sold. d)trade increased regionally but decreased globally because trade networks had shrunk.

The president vetoes a bill proposed to become law by congress. in this situation, what happens to the bill?

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.