Paper balls? A network group about losing weight. In these online groups and communities, there are active young people who are determined to lose weight. They regularly report online, and even regularly "punch in" to supervise each other and exchange slimming experience. Surprisingly, these members are not obese. These members are already very light in weight, but they still insist on becoming paper men.

Mystery is a series of supernatural, thriller and reasoning online novels.

The Yamaguchi group in Japan is the largest mafia organization in Japan, and its members account for about 70% of the total mafia in Japan. By the end of 2008, there were about 22,000 members in the Yamaguchi group, about 1.78 million associate members and an estimated 38,000 members. The Yamaguchi group has activities overseas, including other Asian countries and the United States.

The word "death group" is generally used in large-scale competitions around the world, and in modern competitive competitions, it is also often used in football group matches. Its expression is "death group", which means "the team in this group is strong" or "the most difficult group"

Pulley block:? A pulley device consisting of a crown block and a moving pulley.

Equations are also called "simultaneous equations". Several equations are studied together, so that the unknown satisfies a set of equations of each equation at the same time. The value that can satisfy the unknown number of each equation in the equation set at the same time is called the "solution" of the equation set. The process of finding all its solutions is called "solving equations".