Eventually, the marginal benefit of another park will be less than the marginal cost, so they stop building parks.

最终，总有一座公园的边际效益会小于边际成本，于是他们停止建造公园。

Equilibrium is efficient because the marginal benefit of the last unit consumed equals the marginal cost of that unit.

均衡点最有效率，因为最后一个单位的边际效益等于这个单位的边际成本。

The marginal benefit, in turn, depends on how many units a person already has.

边际收益反过来又取决于一个人已经拥有多少单位。

Water is essential, but the marginal benefit of an extra cup is small because water is plentiful.

水是必不可少的，但额外的杯子的边际效益很小，因为水是丰富的。

When deciding how safely to drive, rational people compare, perhaps unconsciously, the marginal benefit from safer driving to the marginal cost.

在决定如何安全驾驶时，理性的人会将更安全驾驶的边际收益与边际成本进行比较，或许在不知不觉中。

By contrast, no one needs diamonds to survive, but because diamonds are so rare, people consider the marginal benefit of an extra diamond to be large.

相比之下，没有人需要钻石才能生存，但由于钻石非常稀有，人们认为额外钻石的边际效益很大。

The reason is that a person's willingness to pay for any good is based on the marginal benefit that an extra unit of the good would yield.

原因是，一个人愿意为任何利益买单是基于额外单位的福利将产生边际利益。