From the end of the 19th century to the early 20th century, car designers focused their energies on the development and innovation of mechanical engineering. First half of the 20th century, all about the basic structure of the car has been invented, automotive designers begin from the outside to improve on modelling, and successively introduced the aerodynamics, fluid mechanics, human body engineering and industrial modelling design (industrial aesthetics), etc Similarly, while Mr Trump's rhetoric on immigration is intense, his policy is relatively moderate, probably because many businessmen who support his campaign do prefer a moderate approach. The "Muslim ban" does not affect America's Labour supply. Although the pace of deportation has accelerated under Mr Trump, it is worth mentioning that millions of undocumented immigrants have also been deported by Mr Obama. The border wall that Mr Trump has forced Mexico to pay remains a dream of no capital. Even if the government plans to favor skilled workers, it will not necessarily reduce the number of legal immigrants. Ipsos Retail Performance, a consultancy, said retailers were fighting for business after the number of shoppers on high street fell by almost 10% in the first three weeks of December. On Sunday, December 10th, a 21% decline in the British national snow. The determination of this ratio mainly depends on the supply and demand relationship between the two sides and the competition. In general, the interest rate falls when the supply exceeds demand. Interest rates rise when demand exceeds supply. In addition, law, habit and so on also have a larger role. Marx's theory is of guiding significance to explain the question of interest rate decision under socialized production. The charity said it was shocked to find that around 85% of temporary staff suffered a pay deficit while working in the same job for more than three months. It said agency workers that stayed with one employer for more than three months were expected to have the same pay as full-time employees. For a deal that is winning money, it is not as easy to make a deal as it is to make plans to deal with the loss of money. There are many possibilities. High compression ratio if choose low grades of gasoline engine, can make the cylinder temperature rises, the incomplete combustion of gasoline, strong vibration machine, so that the output power down, damage to the parts, fuel consumption and driving. If lower compression ratio engine with high grade oil, can appear "delay" phenomenon, namely the compression ratio is less than the highest point of spontaneous combustion, as will appear incomplete combustion phenomenon, the engine is no good.