边际效用递增规律。
参考答案：
指随着某物品的消费量的增加，该物品的边际效用不断趋于递增。这是网络经济特有的现象。
_______ today, he would get there by Saturday. [ ]
A. If he leaves
B. Was he leaving
C. Would he leave
D. Were he to leave
提出“实业救国”口号、并身体力行的是
[ ]
A、荣氏兄弟
B、陈启沅
C、张謇
D、詹天佑
