These goals are ambitious, but they also remind us to do one thing in the right way. It is not obvious in some analyses, but it is important to note that economic profits include opportunity costs. The profit of an entrepreneur (normal profit) is usually positive, but economic profit can be either positive or negative (loss). That's why the opportunity cost is included: in a completely competitive market, when marginal cost equals marginal revenue, profit maximization or loss minimization conditions arise. If the market price is lower than the total average cost, which means that the economic profit is negative, the entrepreneur needs to compare the value of the loss and the average variable cost. If the business continues to operate, the negative economic profit must not be lower than the average variable cost, otherwise the entrepreneur would rather shut down the company than continue to take the loss. Along with the social network virtualization, the market is not necessarily true place and place, many of today's business is achieved through the computer network, China's largest e-commerce site, taobao is to provide the exchange of virtual market. Taobao, Asia's largest online retail business circle, is committed to creating the world's preferred online retail business, founded by alibaba group on May 10, 2003. Taobao now spans two large parts of C2C (consumer) and B2C (merchant to individual). As of 2008, there were more than 98 million registered users, with the majority of online shoppers in China, covering the vast majority of online shoppers in China. In 2008, the transaction volume was 999.6 billion yuan, accounting for 80% of the online shopping market. breakthrough, but said, the final agreement was established to minimize the trade barriers, and to provide enough time to implement change. A senior tax official with knowledge of the investigation said: The bank of England says Britain is a European banker, and the imf welcomes the progress of Brexit - and that's what happened