除了学加、减、乘、除,还得学a、b、c、d。您看看: "If one were looking for a single criterion by which to distinguish modern economic theory from its classical precursors, he would probably decide that this is to be found in the introduction of the so-called subjective theory of value into economic theory. This revolution in thought broke out almost simultaneously along three fronts, and with it we associate the names of Jevons, Menger, and Walras." ........看看这是什么呀!?这英文字母的排列组合还真不少!!