People who are too happy die younger than their more downbeat（pessimistic） peers(同龄人), claims new research.
　　A study which followed children from the 1920s to old age showed that people who were rated 'highly cheerful' by teachers at school died younger than their more reserved classmates。
　　This was because people who were too happy were more likely to suffer from mental disorders such as bipolar, making them less fearful and more likely to take risks that increase the chance of having a fatal accident.
　　Being too cheerful - especially at inappropriate times - can also rouse anger in others, increasing the risk of a person coming to harm.
　　Researchers from a variety of universities worldwide also discovered that trying too hard to be happy often ended up leaving people feeling more depressed than before, as putting an effort into improving their mood often left people feeling cheated.
　　And magazine articles offering tips on how to be happy were also blamed for worsening depression.
　　One study saw participants asked to read an article offering ways to improve your mood, and follow one of the tips to see how effective it was.
　　Participants then took the advice offered - such as watching an upbeat film - often concentrated too hard on trying to improve their mood rather than letting it lift naturally。
　　This meant that by the time the film had ended, they often felt angry and cheated by the advice given, putting them in a far worse mood than when they had started watching.
　　However, results of the study, published in the journal Perspectives on Psychological Science, revealed that the key to true happiness was much more simple: meaningful relationships with friends and family members.
Study co-author Professor June Gruber, from the department of psychology at Yale University in the United States, said of people who actively tried to be happy: 'When you're doing it with the motivation or expectation that these things ought to make you happy, that can lead to disappointment and decreased happiness. '
　　'The strongest predictor of happiness is not money, or external recognition through success or fame. It's having meaningful social relationships.'
She added: 'That means the best way to increase your happiness is to stop worrying about being happy and instead divert your energy to nurturing the social bonds you have with other people.'
People who are too happy die younger than their more downbeat（pessimistic） peers because________.

A．because they are more likely to suffer from mental disorders.

B．because they have more chance of having traffic accidents.

C．because they have meaningful social relationship.

D．because they stop worry about being happy.

What does the underlined word in Paragraph 2 mean?

A．happy

B．unwilling to show feelings

C．angry

D．narrow-minded

The most important factor(因素) of true happiness is __________.

A．to have meaningful relationships with friends and family members.

B．to stop worry about being happy.

C．to devote your energy to developing the social bonds.

D．to have feeling of success.

Which of the following sentences is correct according to the passage?

A．magazine articles offering tips on how to be happy can help you reducing depression.

B．trying too hard to be happy often leaves people feeling more depressed than before.

C．When you're doing things with the motivation or expectation, that can lead to disappointment and decreased happiness.

D．The strongest factor of happiness is external recognition through success.