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1、大学英语往年六级真题 大学英语往年六级真题：2018年12月英语六级听力Recording 1Here is my baby niece Sarah. Her Mon is a doctor and her dad is a lawyer. By the time Sarah goes to college, the jobs her parents do are going to look dramatically different.In 20XX, researchers at Oxford University did a study on the future of work. Th
2、ey concluded that almost one in every two jobs have a high risk of being automated by machines. Machine learning is the technology thats responsible for most of this disruption. Its the most powerful branch of artificial intelligence. It allows machines to learn from data and copy some of the things
3、 that humans can do. My company, Kaggle, operates on the cutting edge of machine learning. We bring together hundreds of thousands of experts to solve important problems for industry and academia. This gives us a unique perspective on what machines can do, what they cant do and what jobs they might
4、automate or threaten.Machine learning started making its way into industry in the early 90s. It started with relatively simple tasks. It started with things like assessing credit risk from loan applications, sorting the mail by reading handwritten zip codes. Over the past few years, we have made dra
5、matic breakthroughs. Machine learning is now capable of far, far more complex tasks. In 20XX, Kaggle challenged its community to build a program that could grade high-school essays. The winning programs were able to match the grades given by human teachers.Now, given the right data, machines are goi
6、ng to outperform humans at tasks like this. A teacher might read 10,000 essays over a 40-year career. A machine can read millions of essays within minutes. We have no chance of competing against machines on frequent, high-volume tasks.But there are things we can do that machines cant do. Where machi
7、nes have made very little progress is in tackling novel situations. Machines cant handle things they havent seen many times before. The fundamental limitations of machine learning is that it needs to learn from large volumes of past data. But humans dont. We have the ability to connect seemingly dif
8、ferent threads to solve problems weve never seen before.Question 16: What did the researchers at Oxford University conclude?Question 17: What do we learn about Kaggle companys winning programs?Question 18: What is the fundamental limitation of machine learning?Recording 2Weve talked recently about t
9、he importance of sustainable energy. Weve also talked about the different theories on how that can be done. So far, our discussions have all been theoretical. Now I have a practical question for you all. Can you run a one hundred and forty thousand kilogram train on just the steam generated by solar
10、 power? Well, one engineer, Tim councilman believes its possible.And his home city of Sacramento, California should see the technologies first test as part of the upgrading of its rail yard. Councilman, who is an inventor and self-proclaimed steam visionary, is campaigning for a new steam train that
11、 runs without any fire and could run on an existing ten kilometer line, drawing tourists and perhaps offering city commuters a green alternative to their cars. Councilman wants to build an array of solar magnifying mirrors at one end of the line to collect and focus heat onto water filled tubes.This
12、 would generate steam that could be used to fill tanks on a small steam train without the use of fire. Supplying power to trains in this way would offer the shortest distance from well to wheels, he says, with the least amount of energy lost, according to harry valentine, a Canadian engineer who was
13、 researching modern steam technology, a special tank measuring two by ten meters could store over seven hundred and fifty kilowatt hours of energy as high pressure steam enough to pull a two car train for an hour or so. Energy to drive a steam locomotive can be stored in other materials besides wate
14、r.For example, a team at Tohoku University in japan has studied materials that can store large amounts of heat. When he did, these materials turned from a solid into a liquid, absorbing energy as they change phase. The liquid is maintained above its melting point until steam is required, at which po
15、int the liquid is allowed to turn back into a solid, releasing its stored energy. Another team at Nagoya University in japan has tested calcium compound as an energy storage material, heating this chemical compound drives off carbon dioxide gas, leaving calcium oxide.The gas can be stored under pres
16、sure in a tank to recover the energy. The gas is bent back over the calcium oxide. In theory, says Valentine, this can create a high enough temperature to generate superheated steam.Question 19: What has the speaker previously talked about?Question 20: What is Tim Councilman trying to do in Sacramento?Question 21: What has a Japanese research team tried to do?Recording 3Todays crisis in care for older peo
