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. Famous British economist hicks and others argue that the above theory did not consider the factor of income, and therefore unable to determine the level of interest rates, in 1937, and puts forward the is-lm model on the basis of general equilibrium theory. It establishes a theory of interest rates and income at the same time that the four factors of savings and investment, money supply and monetary demand interact. Stocks and shares are closely linked and different. The accounting income follows the historical cost principle and the matching principle, which is conducive to the objective reflection of the business management responsibility of the enterprise management authorities. But, due to the historical cost principle inherent defects, especially according to the present value of revenue and expenses by historical cost line, makes the calculation of accounting earnings lack of inner logical unity, and the matching principle is difficult to carry out, so that the book value of assets can not reflect its real value, cost cannot be fully compensated. And the economic benefit is measured in the current value, which reflects the actual value of the asset, which is beneficial to the full compensation of the cost. Including ambulances, fire engines, sanitation vehicles, TV and radio cars, airport operations, municipal construction projects, etc. Announced on the UK economy in the international monetary fund annual health check results, published in the Treasury's speech, ms lagarde hit back at the recession after the referendum criticism at the upcoming future fund.