122 1-292=929。 Multiplication law, also known as multiplication property, includes exchange law, association law and distribution law. By applying these laws, we can simply calculate some multiplication problems. Multiplicative commutative law is the multiplication of two numbers, the position of the exchange factor, and their products are unchanged.

Multiplicative associative law

Multiply three numbers, the first two numbers are multiplied and then multiplied, or the last two numbers are multiplied and then multiplied, and the product remains the same.

Although there are many kinds of vehicles, their structures are similar. This should be said to be the credit of standardization and the need of large-scale production line. With the development of society, the progress of science and technology and the change of demand, the appearance of railway vehicles has also begun to change, especially the passenger cars are no longer the same old faces. However, their basic structure has not changed obviously, but the specific parts have more scientific and advanced structural design.

Generally speaking, the basic structure of a vehicle consists of five parts: body, underframe, running gear, coupler buffer device and braking device.

The car body is the part of the vehicle carrying goods or passengers, and it is also the basis for installing and connecting other parts of the vehicle. The bodies of early vehicles were mostly wooden structures, supplemented by steel plates and bow bars. Modern automobile body is mainly steel structure or light metal structure.