Uniforms, used for identifying people，are seen almost everywhere in the world. They are a part of everyday life. Let’s look at some of the reasons why people wear uniforms and the types of people that wear uniforms.

Many children have to wear a uniform at school. Boys and girls must wear the same coloured clothes and a school tie. There is often a school badge on the jacket or shirt. There are many reasons for having a school uniforms .Firstly, the uniforms shows that the children attend the same school . It is important for children to feel they belong to a school and that they identify with their school. Secondly, the uniform makes it easy for other people to tell which school the children go to . They know they must be on their best behaviour because people know which school they go to and the children are proud of their school. Thirdly, school uniforms are comfortable,smart clothing. Finally, it is cheaper for parents to buy one set of clothes for their child. Most parents cannot afford to buy lots of expensive, fashionable clothes for their children.

小题1:Are children the only people who wear uniform?

小题2:Why are children on their best behavior when they wear their school uniforms?

小题3:why do police officers wear uniforms?

小题4: can you describe a teenager’s “uniforms”?

小题5:what do teenagers’ clothes tell you about them ?

小题6:what do you want to tell people through the clothes you wear

设R=A，B，C，F=A→B，B→C，ρ=AB，BC
试判断ρ是否为无损分解，并说明理由。