facts about oil Including ambulances, fire engines, sanitation vehicles, TV and radio cars, airport operations, municipal construction projects, etc. 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. It is worth mentioning that Surface Pro is by far the most popular with users of Surface equipment, Surface Pro 4 proportion is as high as 39.7%, Surface Pro 3 also is as high as 21.7%, while older equipment Surface Pro/Pro 2 still has 5.6% and 3.7% of the users. On the Surface Book, however, the average user accounts for just 0.4 per cent of the market, except for the 7.5 per cent share of the first generation, which may be due to a short listing. 3. The role of securities investment As hicks income concept did not specify what is called "equal wealth", and thus the income concept formed the basis of many debates concept, and the theory of accounting earnings, especially the capital preservation theory has a great influence. In accounting, people used to call "maintaining the same level of affluence" as capital preservation. Followed by Edwards and bear published in his 1961 book "the theory of corporate earnings and measurement of the current operating profit is defined as the sales revenue more than the amount of current production and cost of sales, which can realize the cost savings is in this issue of asset price increases, which can realize the history of the cost savings are the pin commodity costs and the difference between the current purchase price; The realized capital gains are the amount of sales revenue greater than the historical cost when dealing with long-term assets. They argue that "these incremental sums provide investors with a reasonable starting point for measuring the scale of relative affluence and a detailed analysis of the company's operating results and comparable financial conditions". They stress that any full income analysis should take into account both realized and unrealized benefits and classify them by source. When are advantageous to occur, such as no record, will not only lead to current income can't reflect, but also can lead to later to sell assets to income and related costs to wrong ratio; Operating earnings and, on the other hand, the production gains is usually produced by different management decisions, and adopted different circulation form, therefore, make the same comment on both, will weaken the role of the income statement.