A-Level课程证书被几乎所有英语授课的大学作为招收新生的入学标准。在中国开设A-Level课程旨在为中国学生提供进入国外大学的有效途径，具体目标为：培养在国内初高中成绩优秀的学生进入世界顶尖大学;培养在国内初高中成绩中等的学生进入世界一流大学;培养在国内初高中成绩一般的学生考取适合自己的大学。大部分英国学生都是用两年的时间修完这种课程，但能力很强的学生有时也可在更短的时间内修完。学生甚至可以直接在国内自学三到四门A-Level课程然后去北京、上海、广州等地英国文化委员会参加考试。这种课程要求学生学习三门或四门主科课程并参加毕业考试，考试合格者即可进入大学就读。学生的考试成绩及其所选修的A-Level课程在很大程度上决定着能否进入理想的大学和学习所选择的学位课程。为了方便同学们的A-Level备考，课窝考试网小编为大家收集整理了A-Level考试的相关信息，供大家学习参考，希望能为同学们的考试提供帮助。
Revision: Contestable markets
The theory of contestable markets states than in imperfect markets, the threat of competition may be enough to prevent the firm acting against the public interest (i.e. keeping prices high and output low).
Conditions for contestable markets:
1. Perfect information - all firms have the same access to technology, no patents etc.
2. Freedom to enter the market legally
3. No sunk costs
In contestable markets incumbent firms are forced to act as if they are in competition, and therefore make only normal profits. If they don't, hit and run entry will occur - in the short run new rivals enter the market and by charging a lower price, take the incumbent firm's market share. Hit and run entry can only occur in barriers to entry and exit is low.
No market is perfectly contestable. Barriers to contestability always exist. What matters is the degree of contestability.
Sunk costs
Sunk costs are costs which are irrecoverable to the owners of the firm if it leaves the market. For example, the Channel Tunnel has very high sunk costs. It is a past expense that cannot be altered by current/future actions.
Sunk costs act as a barrier to entry.
Causes of sunk costs:
No second hand market
Industry specific capital
Future liabilities (e.g. nuclear power plants)
Implications
The theory tells us that all markets can be efficient as long as they are contestable. Therefore regulation is not necessary; in fact it may worsen the situation if regulation acts as a barrier to entry, discouraging potential competition. Instead the government's role should be to:
Make the market more competitive by increasing the degree of contestability
Lower barriers to entry and exit in an industry
Allow take-overs (if they don't prevent competition)
译文：
修正：可竞争市场
可竞争市场理论比不完全市场理论，竞争的威胁可能足以阻止公司对抗公共利益(即保持高价格和低产出)。
可竞争市场的条件：
1。完美的信息-所有的公司都有同样的技术机会，没有专利等。
2。合法进入市场的自由
三。不沉没成本
在竞争激烈的市场中，在职企业被迫采取行动，好像他们在竞争，因此只赚取正常利润。如果他们不这样做，就会进入和运行进入-短期内，新的竞争对手进入市场，并收取较低的价格，采取现任公司的市场份额。进入和跑出进入只能发生在进入壁垒和退出壁垒低。
没有市场是完全可竞争的。可竞争性的障碍总是存在的。重要的是可竞争性的程度。
沉没成本
沉没成本是企业离开市场时不可收回的成本。例如，海峡隧道具有非常高的沉没成本。过去或将来的行动不能改变过去的花费。
沉没成本是进入壁垒。
沉没成本的原因：
无二手市场
行业专用资本
未来负债(例如核能发电厂)
启示
这个理论告诉我们，所有市场都可以是有效的，只要它们是可竞争的。因此，监管是不必要的;事实上，如果监管作为进入壁垒，阻碍潜在的竞争，则可能会使情况恶化。相反，政府的作用应该是：
提高竞争能力，使市场更具竞争力
行业进入和退出的低壁垒
允许接管(如果他们不阻止竞争)
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为了方便同学们的A-Level备考，课窝考试网小编为大家收集整理了A-Level考试的相关信息，供大家学习参考，希望能为同学们的考试提供帮助。
AEIS在线试听课程
