However, there are many firms that have market power or monopoly power, which means that they can increase their price above marginal cost and sustain sales for a long period of time. [1].

但同时许多企业具有一定的市场势力或者说是垄断势力，这意味着他们能够长期将价格定在边际成本之上。

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Thus, a monopoly chooses a quantity qm where marginal revenue equals marginal cost, and charges the maximum price p(qm) the market will bear at that quantity.

这样，垄断者将选择生产当边际收益与边际成本相同时的产量qm。 然后向市场收取那个产量下市场能够承受的最大价格p(qm)。

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Perfect Competition and Monopoly emphasize the roles of average cost and marginal cost curves.

完善竞争和垄断，强调角色的均匀本钱和边沿本钱曲线。

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