水泥混凝土路面有哪些类型？各类型具有什么特点？

0．0000907用科学记数法表示为   ▲  .（保留两个有效数字）.

建筑工程施工安全技术

立柱支撑群架体外侧每隔( )设置一道剪刀撑。

A．3m

B．5m

C．6m

D．8m

综合国力主要由人力、自然力、政治力、经济力、科技力、精神力和国防力等组成。其中经济实力、国防实力和科技实力是综合国力的基本要素。

Researchers found that people become happier and experience less worry after they reach the age of fifty. In fact, they say by the age of eighty-five, people are happier with their life than they were when they were eighteen years old.

The findings came from a survey of more than 340,000 adults in the United States. The Gallup(民意调查) Organization questioned them by telephone in 2008. At that time, the people were between the ages of eighteen and eighty-five.

The researchers asked questions about emotions like happiness, sadness and worry. They also asked about mental or emotional stress.

Arthur Stone at Stony Brook University in New York led the study. His team found that levels of stress were highest among adults between the ages of twenty-two and twenty-five. The findings showed that stress levels dropped sharply after people reached their fifties. Happiness was highest among the youngest adults and those in their early seventies. The people least likely to report feeling negative emotions were those in their seventies and eighties.

Researchers say they do not know why happiness increases as people get older. One theory is that, as people grow older, they grow more thankful for what they have and have better control of their emotions. They also spend less time thinking about bad experiences.

Professor Stone says the emotional patterns could be linked to changes in how people see the world, or maybe even changes in brain chemistry.

The researchers also considered possible influences like having young children, being unemployed or being single. But they found that influences like these did not affect the levels of happiness and well-being related to age.

The study also showed that men and women have similar emotional patterns as they grow older. However, women at all ages reported more sadness, stress and worry than men.

小题1: What can be the best title of the text?

A．Happiness Varies with Ages

B．Experience More, Worry Less

C．The Older, the Wiser

D．Being Young, Being Happy小题2:We can learn from the research that _________.

A．only when people get older will they feel happier

B．stress levels among the youngest are the highest

C．older people tend to be grateful

D．older people usually have no worries小题3:According to the research, when people get older, _________.

A．they miss the old days

B．they are physically weak

C．they have better self-control

D．they are more emotional小题4:What would the author probably talk about next?

A．What influences happiness.

B．How to live better.

C．How to keep happier.

D．Why women are less happier.小题5:The author is intended to _________.

A．advise how to reduce stress

B．introduce a scientific finding

C．describe how to do research

D．talk about human emotions