Chemical industry, that is, the chemical industry, any use of chemical methods to change the composition or structure of substances, or to synthesize new substances, belongs to chemical production technology, that is, chemical processes, and the resulting products are called chemicals or chemical products.

Gas stations refer to refill stations that serve automobiles and other motor vehicles and retail gasoline and engine oil, generally adding fuel oil, lubricating oil, etc.

Mine is a general term for shafts, chambers, equipment, ground buildings and structures that form an underground coal mine production system.

Assembly line, also known as assembly line, is an industrial production method, which means that each production unit only focuses on processing a certain segment of work to improve work efficiency and output; There are seven types of assembly lines: chain line, double-speed chain, plug-in line, mesh belt line, suspension line and roller assembly line.

Railway tunnels are passages dedicated to train transportation. When the railway passes through the mountainous area, due to the limited traction capacity and the maximum slope limit (less than 24%), it is necessary to overcome the elevation obstacle. It is a reasonable choice to excavate a tunnel to cross the mountain. Its function is to shorten the line, reduce the slope, improve the operating conditions and improve the traction capacity. According to its location, it can be divided into three categories: mountain tunnels that pass under mountains or hills in order to shorten the distance and avoid large slopes; underwater tunnels pass under rivers or under the sea to pass through rivers or straits; In order to meet the needs of railways passing through large cities, the urban tunnels are called urban tunnels.