你认为界定一门科学的特征是什么?经济研究有这些特征吗?你认为宏观经济学应该被称为科学吗?为什么应该或为什么不应该? What do you think are the defining characteristics of a science? Does the study of the economy have these characteristics? Do you think macroeconomics should be called a science? Why or why not?