发布时间 : 星期六 文章(word完整版)2018年北京高考英语试卷及答案,推荐文档更新完毕开始阅读f07803f7effdc8d376eeaeaad1f34693dbef104e
C
Plastic-Eating Worms
Humans produce more than 300 million tons of plastic every year. Almost half of that winds up in landfills(垃圾填埋场)， and up to 12 million tons pollute the oceans. qSo far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms.
Researchers in Spain and England recently found that the worms of the greater wax moth can break down polyethylene, which accounts for 40% of plastics. The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms' chewing alone was not responsible for the polyethylene breakdown, the
researchers made some worms into paste(糊状物) and applied it to plastic films. 14 hours later the films had lost 13% of their mass--apparently broken down by enzymes(酶)from the worms' stomachs. Their findings were published in Current Biology in 2017.
Federica Bertocchini, co-author of the study, says the worms' ability to break down their everyday food-beeswax--also allows them to break down plastic \is a complex mixture, but the basic bond in polyethylene, the carbon-carbon bond, is there
as well, \break this bond. \
Jennifer Debruyn, a microbiologist at the University of Tennessee, who was not involved in the study, says it is not surprising that such worms can break down polyethylene. But compared with previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)?
Bertocchini agrees and hopes her team’s findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process-not simply \of worms thrown on top of the plastic.”
43. What can we learn about the worms in the study? A. They take plastics as their everyday food. B. They are newly evolved creatures. C. They can consume plastics. D. They wind up in landfills.
44. According to Jennifer DeBruyn, the next step of the study is to . A. identify other means of the breakdown B. find out the source of the enzyme C. confirm the research findings D. increase the breakdown speed
45. It can be inferred from the last paragraph that the chemical might .
A. help to raise worms B. help make plastic bags C. be used to clean the oceans D. be produced in factories in future 46. What is the main purpose of the passage?
A. To explain a study method on worms. B. To introduce the diet of a special worm. C. To present a way to break down plastics. D. To propose new means to keep eco-balance.
D
Preparing Cities for Robot Cars
The possibility of self-driving robot cars has often seemed like a futurist's dream, years away from materializing in the real world. Well, the future is apparently now. The California Department of Motor Vehicles began giving permits in April for companies to test truly self-driving cars on public roads. The state also cleared the way for companies to sell or rent out self-driving cars, and for companies to operate driverless taxi services. California, it should be noted, isn't leading the way here. Companies have been testing their vehicles in cities across the country. It's hard to predict when
driverless cars will be everywhere on our roads. But however long it takes, the technology has the potential to change our transportation systems and our cities, for better or for worse, depending on how the transformation is regulated.
While much of the debate so far has been focused on the safety of driverless cars(and rightfully so), policymakers also should be talking about how self-driving vehicles can help reduce traffic jams, cut emissions(排放) and offer more convenient, affordable
mobility options. The arrival of driverless vehicles is a chance to make sure that those vehicles are environmentally friendly and more shared.
Do we want to copy- or even worsen- the traffic of today with driverless cars? Imagine a future where most adults own individual self-driving vehicles. They tolerate long, slow journeys to and from work
on packed highways because they can work, entertain themselves or sleep on the ride, which encourages urban spread. They take their driverless car to an appointment and set the empty vehicle to circle the building to avoid paying for parking. Instead of walking a few blocks to pick up a child or the dry cleaning, they send the self-driving minibus. The convenience even leads fewer people to take public transport——an unwelcome side effect researchers have already found in ride- hailing(叫车) services.
A study from the University of California at Davis suggested that replacing petrol-powered private cars worldwide with electric, self-driving and shared systems could reduce carbon emissions from transportation 80% and cut the cost of transportation infrastructure
(基础设施) and operations40%by2050. Fewer emissions and cheaper travel sound pretty appealing. The first commercially available driverless cars will almost certainly be fielded by ride-hailing services, considering the cost of self-driving technology as well as liability and maintenance issues(责任与维护问题).But driverless car ownership could increase as the prices drop and more people become comfortable with the technology.
Policymakers should start thinking now about how to make sure the appearance of driverless vehicles doesn't extend the worst aspects of the car-controlled transportation system we have today. The coming technological advancement presents a chance for cities and states to develop transportation systems designed to move more people，and
more affordably. The car of the future is coming. We just have to plan for it.