Solution: as long as the gasoline in the tank is exhausted, the extra gasoline vapor in the tank can be fired into the cylinder by the negative pressure of the engine, and no gasoline vapor will overflow. In the 1920s and 1930s, the great depression forced western economic theorists to reflect on the definition of the market. The final answer is completely laissez faire is not enough, the invisible hand sometimes does not exist, market failure, government should be on economic activity on the "total" intervention, so "macroeconomics" was born. Roosevelt also accepted Keynes's proposal to impose a "New Deal" on government intervention in the economy. It has now formed the world's most consensus-building government: fiscal policy, monetary policy, and, of course, none of these "new" policies. Palmer said: "I'm worried about the British retailers are now in the midst of a perfect storm, interest rate decisions in November, rising inflation, real wages, falling credit availability and the UK to take off the European uncertainty increased, these during the Christmas season for caused an unprecedented pressure on household budgets, pushed consumer confidence to historic lows. "Historically, the concept of income has first appeared in economics. Adam Smith, in the wealth of nations, defined income as "the amount of consumption that is not eroded by capital", and saw it as an increase in wealth. Later, most economists inherited and developed this view. 1890, ai (Alfred Marshall Maarshell) in its "the principles of economics," the Adam Smith's "wealth increase" enterprise, introduced the concept of earnings, is proposed to distinguish the entity capital and value-added benefits of economic benefits. Overnight, the benchmark 10-year Treasury note fell 8/32, yielding 2.480%, its highest level in nine months. It even hit 2.5 per cent on Wednesday. The fund said last year that it would grow 1.1% in 2017 and then increase its forecast to 2%.