Definition: a good is public if the marginalproduction cost is lower than the marginal billing cost.
定义：一个好的公众事物仅当其边际产值小于其边际广告值。
2
Bundling selling is a kind of popular method for selling information goods. And this method should be taken into account on the basis of low marginalproduction cost.
捆绑式销售是当前比较流行的信息商品销售方法之一，这种方法充分考虑了生产时的低边际成本。
3
Moreover, as less fertile or accessible land is brought under cultivation, the marginal cost of food production rises.