Sunglasses allow better vision in bright daylight, and may protect one's eyes against damage from high levels of ultraviolet light. Typical sunglasses are darkened for protection against bright light or glare; some specialized glasses are clear in dark or indoor conditions, but turn into sunglasses when in bright light. Most sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be ordered. Specialized glasses may be used for viewing specific visual information (such as stereoscopy) or 3D glasses for viewing three-dimensional movies. Sometimes glasses with no corrective power in the lenses are worn simply for aesthetic or fashion purposes. Even with glasses used for vision correction, a wide range of designs are available for fashion purposes, using plastic, wire, and other materials. The trend is the direction of market movements. There are three trends: uptrend, downtrend and oscillation. There are three main trends, secondary trends and short trends. When talking about trends, you must have corresponding cycles and corresponding references, and the trend will always run in the direction of the least resistance of the market. In the works of the horse writers terence and Cicero, the word has evolved into the meaning of the book and the stylistic meaning, expressing the specific way of expressing ideas in words. English, French style and German stil all came from this. The Chinese style has appeared in the writings of the jin people (see ge hong "hold the park", etc.), refers to the character of the person. In the south Korean period liu xie's "wen xin diao long", move the style pattern of the article. In the painting history of the tang dynasty, the style was used as the comment language of painting art. Since modern times, people have used this word extensively in the fields of aesthetics, literature, art, literary criticism and so on. What the hacking Arsenal does is not vandalism, they are a network of technical personnel, keen on scientific exploration, computer science research. In Hacker circles, the word Hacker undoubtedly has a positive meaning, such as: system Hacker is familiar with the design and maintenance of operation; Password hacker is good at figuring out the user's password, and if computer hacker is a computer savvy person, he is a master of other people's computer systems The hackers were meant to be the workers who cut wood with axes, and the first to be introduced into the computer industry dates back to the 1960s. Computer at the university of California, Berkeley professor Brian Harvey this word once wrote in the textual research, then at the Massachusetts institute of technology (MIT) of the students are usually divided into two pie, it is a tool, means a mamma students, grades and grade a; The other is the so-called "hacker", who often skip classes and love to sleep in class, but at night, he likes to do extracurricular activities