求翻译：对于寡头在市场中的行为，已有不少的理论和模型，但与其他三种市场理论相比，寡头理论要复杂得多，具体表现为：①种类多。有少数纯质寡头垄断，双头纯粹寡 头垄断，双头异质寡头垄断，等等。②行为多样。寡头相互依存，可能是相互猜测的独立行为，也可能是各种不同方式，不同程度的勾结和协作。③竞争方式不同， 可能是价格竞争也可能是非价格竞争。是什么意思？

For the behavior of oligopoly in the market, there are many theories and models, but compared with the other three market theory, oligopoly theory is much more complex, specifically as follows: ① variety. There are few pure quality oligopoly, pure oligopoly-headed, double-headed heterogeneous oligop