【分析解答题】

A、theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future conservation. Newton’ s theory of gravity was based on an even simpler model, in which bodies attracted each other with a force that proportional to a quantity called their mass and inversely proportional to the square of the distance between them.