已知在等差数列{a_n} 中，a₅+a₁₁=16,a₄=1 ，则 a₁₂ 的值是(     )

   More than 50,000,000 people live in the rainforests of the world and most of them do not hurt the forest they live in. They eat the fruits that grow on the forest trees, but they do not cut them down. They kill some animals to eat, but they do not destroy them.
When we cut down the rainforests, we destroy these forest people, too. In 1900, there were 1,000,000 forest people in the Amazon forest. In 1980, there were only 200,000.
   The Yanomami live along the rivers of the rainforest in the north of Brazil. They have lived in the rainforest for about 10,000 years and they use more than 2,000 different plants for food and for medicine. But in 1988, someone found gold in their forest, and suddenly 45,000 people came to the forest and began looking for gold. They cut down the forest to make roads. They made more than a hundred airports. The Yanomami people lost land and food. Many died because new diseases came to the forest with the strangers.
   The Yanomami people tried to save their forest, because it was their home. But the people who wanted gold were stronger.
Many forest people try to save their forests. Chico Mendes was famous in Brazil because he wanted to keep the forest for his people. “I want the Amazon forest to help all of us-forest people Brazil, and all the Earth,” he said. A few months later, in December 1988, people who wanted to cut down the forest killed Chico Mendes.
   In Borneo, people were cutting down the forest of the Penan people to sell the wood. The Penan people tried to save their rainforest. They made blockades across the roads into the forest. In 1987, they closed fifteen roads for eight months. No one cut down any trees during that time.
   In Panama, the Kuna people saved their forest. They made a forest park which tourists pay to visit.
  The Gavioes people of Brazil use the forest, but they protect it as well. They find and sell the Brazil nuts(坚果) which grow on the forest trees.

阅读《醉翁亭记》，回答后面的题。
                                                                                醉 翁 亭 记
        环滁皆山也。其西南诸峰，林壑尤美，望之蔚然而深秀者，琅琊也。山行六七里，渐闻水声潺潺而泻出于两峰之间者，酿泉也。峰回路转，有亭翼然临于泉上者，醉翁亭也。作亭者谁？山之僧智仙也。名之者谁？太守自谓也。太守与客来饮于此，饮少辄醉，而年又最高，故自号曰醉翁也。醉翁之意不在酒，在乎山水之间也。山水之乐，得之心而寓之酒也。
        若夫日出而林扉开，云归而岩穴暝，晦明变化者，山间之朝暮也。野芳发而幽香，佳木秀而繁阴，风霜高洁，水落而石出者，山间之四时也。朝而往，暮而归，四时之景不同，而乐亦无穷也。
        至于负者歌于途，行者休于树，前者呼，后者应，伛偻提携，往来而不绝者，滁人游也。临溪而渔，溪深而鱼肥，酿泉为酒，泉香而酒冽，山肴野蔌，杂然而前陈者，大守宴也。宴酣之乐，非丝非竹，射者中，弈者胜，觥筹交错，起坐而喧哗者，众宾欢也。苍颜白发，颓然乎其间者，太守醉也。
        已而夕阳在山，人影散乱，太守归而宾客从也。树林阴翳，鸣声上下，游人去而禽鸟乐也。然而禽鸟知山林之乐，而不知人之乐；人知从太守游而乐，而不知太守之乐其乐也。醉能同其乐，醒能述以文者，大守也。太守谓谁？庐陵欧阳修也。