nab profit The optimal combination of benefits and risks is the best combination of benefits and risks. If the benefit is certain, the risk is minimized; Originated in ancient human market trading place for a fixed period of time or place, after the urban growth and prosperity, live in the city of adjacent area farmers, craftsmen, artisans, will start to deal with each other and contribute to the economy of the city. Obvious, the best way to trade is in the city there is a centralized, as market, can let the people in the provision of goods and business services, convenient for people to find goods and business contacts. When a city's market becomes large and more open, the city's economic vitality is also relatively growing. According to the pantheon of macroeconomics Klaus weiss peterson (Claus Vistesen), which suggests that the management committee "is still not willing to" the strong growth prospects into the core of higher inflation forecasts. The essence of the plan is to identify the objectives and the ways and means to achieve them. Therefore, how to move towards the established goal and achieve the organizational goal, the plan is undoubtedly the standard of all behaviors in the management activities. It directs people in different Spaces, time and positions to achieve their goals in an orderly fashion around a general goal. If there is no planning instruction, the manager will be shown as aimless aimlessness, and the manager will be shown as the policy decision to make decisions and make decisions. The result must be the chaos of organizational order, and the result of a lot of work. In a modern society, it can be said that almost every undertaking, every organization, and even every person's activities cannot have no blueprint. Rolling planning laws is according to the principle of "almost fine far" a certain period of the plan, then according to the plan implementation and environmental changes and adjustments and changes to the plans for the future, and by backward, combine short-term and medium-term plans of a kind of planning method. In the American society of automotive engineers standards SAEJ 687 c for automobile is defined as: power driven by itself, with a driving device, can in a fixed orbit outside the road or on regional transport passenger and cargo or vehicle traction vehicles. Cars are divided into bicycles and trains according to the overall structure. Cycling is a basic form. 4 x 2, 6 x 4, 4 x 4 and 6 x 6 are used to represent the driving characteristics. The previous number represents the total number of wheels (double tire and still count a wheel), and the latter number indicates the number of driving wheels. If all wheels are driven wheels are called all-wheel drive vehicles. The train is made up of a tractor or a bicycle trailer or semi-trailer. Car generally can be divided into the following categories, according to the use cars, buses, freight cars (commonly known as the truck), off-road vehicle, traction motor, dump truck, special vehicles, semi-trailer and special semi-trailer.