Yunnan's Pu'er County."可知，茶马古道的起点是中国云南的普洱县。

6．The "Tea Horse Road" is now most popular with ________.

A．businessmen B．explorers

C．historians D．tourists

解析：选D　细节理解题。由最后一段"Today, the 'Tea Horse Road' is a hot spot for tourists."可知，茶马古道现在是深受旅游者青睐的景点。

If you need one more reason to be thankful, here it is.

One recent study from the University of California San Diego's School of Medicine found that people who were more grateful actually had better heart health."They showed better well­being, a less depressed mood, less tiredness and they slept better，" said the study's author, Paul J．Mills.

Researchers at the universities of Utah and Kentucky observed that stressed­out law students who characterized them selves as optimistic actually had more disease­fighting cells (细胞) in their bodies.

Robert Emmons, a professor at UC Davis, said there's even more evidence. People who keep a gratitude journal have a reduced fat intake - as much as 25 percent lower. Stress hormones (激素) like cortisol are 23 percent lower in g rateful people. And having a daily gratitude practice could actually reduce the effects of aging to the brain.

"Being thankful has such a big effect because of the feelings that go along with it，"Emmons said."Gratitude works because it recruits other positive emotions (情绪) that have direct physical benefits."Research shows that when we think about what we appreciate, the calming part of the nervous system works and that can have protective benefits on the body.

"Some people may not be grateful by nature but it is a habit you can get used to，"said Dr.Norman Rosenthal, a doctor and author of Winter Blues."One ve ry good way is being aware of comparing up.It almost always leads to unhappiness because you can always find a person who is more advantaged than you are."

Norman says all you have to do is think about being grateful."Some people say they don't have anything to be grateful for，"Norman said."If you take such a person to find one little thing to be grateful for and focus on that, you find over time that the feeling of gratitude can change the way they see their lives."

语篇解读：本文是说明文。研究表明感激不但使我们有好的人际关系，而且对我们的健康大有好处。

7．How does the author mainly explain the reason to be thankful?

A．By presenting research findings.

B．By making comparisons.

C．By analyzing causes.

D．By giving examples.

解析：选A　推理判断题。第二、三、四段列举了各个实验、证据解释了我们为什么要感激。

8．Why does the author mention law students in Paragraph 3?

A．To advise us to be optimistic.