profits will be maximized when marginal revenue A broad market is a group of vendors and individuals who are associated with other vendors and individuals to buy and sell certain goods. The size of the market, the size of the market, is the number of buyers. Commercial vehicles: vehicles used for transporting personnel and goods in design and technical features, and can be tractor-trailer. Passenger cars are not included. Commercial vehicles are divided into three categories: passenger cars, vans and semi-trailer tractors. The passenger bus subdivided into small passenger car, city bus, coach, tourist bus, articulated bus, coach, cross-country coach and private bus. Goods vehicles are subdivided into general goods vehicles, multi-purpose lorries, full trailer tractors, off-road trucks, special operations vehicles and special goods vehicles. Tubes in today's world is filled with harmony and polarization phenomenon, but still people are eager to build a better future, enable people to realize self-management, and supporting the social institutions really serve the people. 3. Remove the gasoline pump in the car 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.