关于A-level考试，在这边小编真诚地建议同学们，大家就把contestable market当作一个new market，在你还不是很熟悉他的时候，不要把他与其他market structure联系起来，等你对他认识充分的时候，你尽可以大胆地将之与其他market 进行比较，不过切记，距离产生美。
　　关于contestable market的几大特点要牢牢把握：
　　定义如下:
　　Contestable market: any market structure where there is a threat that potential are free and able to enter this market.
　　特点如下：
　　The number of firms in the industry may vary from one (a monopolist) having complete control of the market, to many, with no single firm having a significant share of the market.
　　In a contestable market, there is freedom of entry to and exit from the market. This means there will be no sunk costs.
　　Firms are short-run profit maximisers, producing where MC = MR.
　　There is perfect knowledge in the industry.
　　The potential forhit-and-runcompetition exists.
　　重中之重点小编已经画出来了，大家务必注意，在写作的时候你会发现永远离不开对low barriers，sunk cost的讨论，从而努力证明某某市场具有contestability。
　　所以，这里也要求同学们独具慧眼地在材料中寻找可能跟contestability相关的蛛丝马迹。