题干

超临界流体是介于气态和液态之间的一种新的状态。目前应用最广的是超临界二氧化碳,在化学工业上可取代氟利昂等溶剂、发泡剂。下列有关超临界二氧化碳的说法中错误的是(   )

A:超临界二氧化碳由CO2分子构成

B:超临界二氧化碳是新合成的一种物质

C:用超临界二氧化碳溶解物质后,可在常温常压下使二氧化碳挥发除去

D:用超临界二氧化碳代替氟利昂可减轻对臭氧层的破坏

上一题 下一题 0.0难度 选择题 更新时间:2019-07-13 10:08:46

答案(点此获取答案解析)

B

同类题2

   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.