阅读下面短文和问题，根据短文内容，在相应题号后的横线上写下相关信息（不多于五个单词），
完成对该问题的回答。答语要结构正确，书写工整，字迹清楚。
Anxiety is a real emotional (情绪的) disturbance. From time to time, everyone worries about his or her
health, family, money, and school. However, when a person has anxiety, they worry all the time, even when
nothing is wrong. Physical symptoms (症状) can also happen. They may have trouble falling asleep, think
about a particular situation for a long time and find it difficult to think of something else. Sometimes they may
feel restless and sweaty, and have trouble concentrating. They may overeat or lose their appetite. They may
also have a feeling that something bad is going to happen.
In fact, anxiety is extremely common; it is estimated that about 13% of the United States' population has
anxiety. A study shows anxiety affects all ages, including teenagers and children.
Many teenagers have anxiety and feelings of great stress, worry, fear and panic. Anxiety can affect many
aspects of a teenager's life. If a teenager is always anxious and worried, it might affect their ability to make
friends, perform well in school, and try new things. It is doubtful whether he or she can fully enjoy life. So
the most important thing is to understand that anxiety can be treated and to help them have a happy and healthy
life.
1. What is anxiety according to the passage?
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2. When a person has anxiety, what is the common symptom?
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3. What is the function of paragraph 2 in the organization of the passage?
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