日本熟妇在线观看日本人妻综合久|娇妻在厨房被朋友玩得呻吟|亚洲欧美在线观看一区二区三区|美味人妻2在线看|日本熟女熟妇成熟|被蹂躏的人妻日本电影|sex日本熟妇|欲女校花放荡|忘穿内裤在公交车摸喷水|www.日本av电影,91少妇性色按摩,和朋友人妻偷爱bd中文字幕口述和人妻 ,特黄熟妇丰满人妻

Machinery refers to the general name of machines and mechanisms. Machinery is a tool that helps people to reduce their work difficulty or effort. Things like chopsticks, brooms and tweezers can be called machines. They are simple machines. And complex machines are made up of two or more than two simple machines. Usually, these more complex machines are called machines. From the point of view of the structure and motion mechanism and machine, there is no difference between general machinery.

Machinery, originally referred to as "ingenious design", as a general mechanical concept, can be traced back to the ancient Rome period, mainly for distinction and manual tools. The term "machine" in modern Chinese is the generic name of the English machine. Mechanical characteristics are: mechanical is a combination of man-made physical components. There is a definite relative motion between the parts of the machine. Therefore, the machine can convert mechanical energy or complete useful mechanical work, which is the most basic concept in modern mechanical principle.