A、Uniforms save civil clothes. B、Uniforms make people look better. C、Uniforms save on laundry bills. D、Uniforms are more durable

Americans advocate individuality more than any other things, however, they love and respect few things more than a uniform, which is quite contrary to their preference. Why are uniforms so popular in the United States?
     (20)Among the arguments for uniforms, one of the first is that in the eyes of most people they look more professional than civilian clothes. People have become conditioned to expect superior quality from a man who wears a uniform. The television repairman who wears a uniform tends to inspire more trust than one who appears in civilian clothes. Faith in the skill of a garage mechanic is increased by a uniform. What an easier way is there for a nurse, a policeman, a barber, or a waiter to lose professional identity than to step out of uniform?(21)Uniforms also have many practical benefits. They save on other clothes. They save on laundry bills. They are often more comfortable and more durable than civilian clothes.
    Primary among the arguments against uniforms is their lack of variety and the consequent loss of individuality experienced by people who must wear them. Though there are many types of uniforms, the wearer of any particular type is generally stuck with it, without change, until retirement. When people look alike, they tend to think, speak, and act similarly, on the job at least.(22)Therefore, if you don’t like to look like or act like others, occupations with uniforms may not be your ideal choice.
Questions 20 to 22 are based on the passage you have just heard.
20. What does the author want to show by listing a few occupations?
21. Which of the followings is not the practical benefit of uniforms?
22. What is the author’s suggestion to those who prefer individuality?