题目

[化学——选修5：有机化学基础](15分) 已知：RX＋MgRMgX(RX为卤代烃，X为卤族原子)，生成的卤代烃基镁与具有羰基结构的化合物(醛、酮等)发生反应，再水解就能合成各种指定结构的醇： 现以2­丁烯和必要的无机物为原料合成3,4­二甲基­3­己醇，进而合成一种分子式为C10H16O4的具有六元环的物质J，合成线路如下(G的核磁共振氢谱有三组峰)： 请按要求填空： (1)3,4­二甲基­3­己醇是：________(填代号)，E的结构简式是________。 (2)C→E的反应类型是________，FFive times in the earth’s history, some three-quarters of all living species disappeared forever-and within a short period of time. Those species losses stand for a major change in the planet’s ecology(生态学). Clues to these changes can be seen in the fossils(化石)and rock layers.Today, human activities are driving species to die out at a rate never seen before. And this loss of species really does matter, said Anita Narwani. She works at the University of Michigan in Ann Arbor. That’s because the diversity(多样性)of species in an ecosystem provides people with all types of services we can’t do without.Trees provide oxygen for us to breathe. At the same time, they remove carbon from the air which is a cause of global warming. Plants help clean air and water. Animals move seeds from one area to another. A broad range of living resources also provides people with food, shelter and medicine.Narwani wanted to find out how important the diversity of species is for people. So she teamed up with other ecologists to review more than 1,700 studies. They found that more diverse parts of the earth tend to do well in things like removing carbon and providing us with wood and other natural resources. They were also better at keeping fisheries large and healthy so that they could feed many people.Unfortunately, the diversity of species is in steep drop. It is too soon to say that the earth is undergoing a sixth mass extinction, Narwani said. She said a mass extinction means the loss of 75 percent of species over 2 million years or less. We haven’t lost that many – at least not yet. But according to her, if species losses continue so fast, such a mass extinction could occur in just 300 years.The new findings highlight the potential for humans to use up many of the resources on which we now depend. As people learn more, however, they can take steps to lessen those risks. People should protect ecosystems so that they can continue to provide us with their services.1.What’s the writer’s purpose in giving the examples in Paragraph 3?A. To tell us how we get our food and resources.B. To show the importance of the diversity of species.C. To tell us the use of each species.D. To show the writer is very learned.2.The underlined word “They ” in Paragraph 4 refers to .A. humansB. Narwani and her teamC. natural resourcesD. various species3.Narwani and her team found that .A. many people know the importance of protecting wildlifeB. many species die out because of human activitiesC. making good use of natural resources benefits peopleD. rich diversity of species greatly benefits people4. We can learn from Paragraph 5 that .A. the world’s species are dying out in a very fast rateB. we’ll lose 75 percent of species on the earthC. the earth is undergoing a sixth mass extinctionD. a mass extinction of species will occur in 300 years