久久精品无码AV,亚洲精品不卡无码福利在线观看,亚洲熟妇无码AV,男人扒开女人双腿猛进视频

       The trolley case is a travel friend, a reliable trolley case can bring convenience and pleasure to your movement, and can make you rest assured that people will not be on the road. What's interesting is that looking at the development history of suitcases, what is presented is not only the past and present of this tool, but also the changes in tourism history and transportation.

        From the coarse cloth wraps commonly seen in costume dramas to the later various wood, leather or iron suitcases, although it has been evolving, until the middle and late 19th century, the common suitcases were still huge and bulky and very inconvenient to carry. When the traffic was developed in the late 19th century, and the tourism industry began to flourish, the luggage has really made great progress. In 1972, Bernard Sadow from the United States invented a hand luggage with 4 wheels and a belt and obtained a patent. After that, wheeled suitcases began to spread slowly. But it wasn't until 1991 that the common suitcases with telescopic poles began to appear. A pilot named Bob Plath added 2 wheels and a retractable handle to the wheeled suitcase, invented the trolley case and obtained a patent, and finally established the basic shape of the suitcase today. ABS resin is easy to process and formability, elasticity, strength, heat resistance and corrosion resistance are good, and it has a wide range of uses. It is commonly used in machinery, electricity, textiles, automobiles and shipbuilding industries. However, it is prone to scratches and its toughness, heat resistance and cold resistance are not small compared to the popular PC materials today.