1、大学英语六级 138 及答案解析(总分：448.03，做题时间：132 分钟)一、Part I Writing (3(总题数：1，分数：30.00)1.For this part, you are allowed 30 minutes to write a short essay entitled Food Safety Problem. You should write at least 150 words following the outline given below in Chinese: 1. 我国食品市场存在的问题。 2. 怎样解决食品安全问题。 3. 结论。 （分数：30.00
2、）_二、Part II Reading C(总题数：1，分数：71.00)Designs on life Even if youre thinking big, you usually have to start small. It is especially true for a group of Swiss students who found that big means counting to infinity. The team was drawing up a blueprint for the worlds first counting machine made entirely
3、 of biological parts. Although they had their sights on loftier numbers, they opted to go no higher than two. If the plan worked, it would be a proof-of-principle for a much larger tallying device(计算装置). The group, from the Federal Institute of Technology (ETH) in Zurich, was one of 17 teams present
4、ing their projects at the first international Intercollegiate Genetically Engineered Machine (IGEM) competition, held at the Massachusetts Institute of Technology (MIT) in Cambridge on 5 and 6 November. The event attracted students from all over the world to design and build machines made entirely f
5、rom biological components such as genes and proteins. They drew up grand designs for bacterial Etch-a-Sketches, photosensitive t-shirts, thermometers and sensors. And if none of the designs succeeded completely, that was more because of the limitations of the new-born science of synthetic biology th
6、an any lack of enthusiasm, creativity or hard work. Synthetic biology Synthetic biology aims to merge engineering approaches with biology. Researchers working at the most basic level are copying simple biological processes, such as the production of a protein from a gene. They break the process down
7、 into its component elements, such as a gene and the pieces of DNA and other molecules that control its activity. They then string these elements together to build a module they know will behave in a particular way say, oscillate between producing and not producing a protein, or produce a protein th
8、at can switch another module on or off. It is these kinds of components oscillators (震荡器) and switches that engineers order from suppliers and link together to build more complex electronic circuits and machines. Synthetic biologists are trying to develop a similar armoury of biological components,
9、dubbed BioBricks, that can be inserted into any genetic circuit to carry out a particular function. Scientists at MIT have established a Registry of Standard Biological Parts, a catalogue of BioBricks that theoretically can be ordered and plugged into a cell, just as resistors and transistors can be
10、 ordered and plugged into electronic circuitry. But it is hard to find scientists who are trained and interested in both biology and engineering to fuel the development of this new science. So, like true engineers, the founding synthetic biologists are trying to build their future colleagues from th
11、e ground up. To do so, they have commandeered a time-honoured engineering tradition: the student competition. The IGEM event began life as a project class for MIT students in 2003. Last year, it was thrown open to other US universities, and this year it went international. The organizers hope to att
12、ract 30 to 50 teams next year, including some from Asia. Competitive culture Much like the robot competitions that tap into students desire to build something cool, the IGEM jamborees (国际性少年大会) fire the participants natural curiosity hopefully encouraging biologists to learn something from engineers
13、, and vice versa. “If you want to make something in this field, you cant just get some glue out and stick two cells together,“ says Randy Rettberg of MIT, who organized the competition. “You have to learn some biology to do it, and its easy to do that during the competition because you know exactly
14、why youre doing it.“ This year, the teams presented an eclectic selection of designs. Students from the University of Cambridge, UK, tried to make a circuit that could control the movement of Escherichia coli bacteria. They aimed to engineer the bacteria to contain a switch governing their sensitivi
15、ty to the sugar maltose. With the switch off, the microbes would ignore the sugar. Tripping the switch would make the bacteria sensitive to the sugar and induce them to move towards it. In the end, the group like almost every other entrant had trouble completing assembly of its genetic parts in time
16、. Many of the other students also tackled problems related to bacterial communication and motion. The team from Pennsylvania State University designed a bacterial relay race, which it hoped would bring synthetic biology into the realm of sports an innovation that won it an award for the Best New Spo
17、rt at the end of the competition. A team from the University of Oklahomas Advanced Center for Genome Technology in Norman tried to exploit the sugar arabinose as an engine to drive bacterial motion. Teams from the University of Toronto and the University of California, San Francisco, built concepts
18、for bacterial thermometers; and groups from Harvard, Toronto and Princeton designed bacterial illustrators and Etch-a-Sketches. Detection and sensing were also popular, with groups from Davidson College and MIT focusing in this area. And a lab at the California Institute of Technology tackled a prob
19、lem raised at last years event: designing biological memory. Students from the University of Texas demonstrated the worlds first bacterial photography system. The team engineered a plate of E. coli so that they would respond to light and has since used the invention to take numerous photos, includin
20、g shots of the groups adviser, Andrew Ellington. Piece by piece As well as helping students to bridge the divide between disciplines, the competition gave them firsthand experience of life in the lab. All hit obstacles assembling their parts into coherent devices. It is still difficult to dissect th
21、e different genetic components of the circuits, stitch them together and get them to work in live cells. As Emanuel Nazareth reported, the students all learned one hard truth: “You can never allocate enough time for assembly.“ This hints at a larger problem in synthetic biology. The field aims to bu
22、ild up a library of parts that can be interchanged in circuits with minimal effort. But that goal is not yet a reality as DNA sequencing and assembling technologies are still a bit too expensive and complex. “Were not organized at the community level around fabrication,“ says MITs Drew Endy, one of
23、the founders of the field and of the Registry of Standard Biological Parts. These difficulties need to be overcome before biological components will be as easy to deploy as their engineering counterparts. Another learning experience was the reminder that, even stripped down to its basic components,
24、biology can be complex and unpredictable. A team from the University of California, Berkeley, for instance, tried to design an entirely new way for cells to communicate. This is a potentially important because it would enable cells to send and receive information, forming interlocking cell circuits
25、instead of relying on simple gene circuits built in single cells. The team hoped to exploit a natural method used by bacteria to exchange genetic information. In this, two bacteria connect their respective cell walls together using a structure called a pilus(菌毛). The group managed to trigger the con
26、nection response with synthetic circuits. But the bacteria turned out to be so eager to join up that they did so in huge bunches and once they did, it was hard to separate them. “They dont really conjugate one at a time,“ said team spokeswoman Melissa Li. “They can go, but they cant stop.“ The livin
27、g end As Rettberg points out, there are a lot of sceptics. “Theres a big question, which is: can you build simple biological systems out of interchangeable parts and make them work in living cells?“ he says. “We think you can, but theres a lot of people who think the other way and say biology is sim
28、ply so complex you cant do it.“ Given these concerns, it is no surprise that researchers have decided to keep things as simple as possible. As Robin Knzler said in introducing the project: “In the beginning we talked about counting to infinity, but we thought maybe wed start by counting to two.“ Des
29、pite this narrowed scope, the students faced a formidable challenge. They designed a series of devices: the first takes in a signal, which is then passed to an event processor. This processor a genetic circuit splits the signal into two components. A third circuit does the counting and generates a r
30、ead-out. （分数：71.00）(1).A group of Swiss students designed the worlds first counting machine made entirely of biological parts.（分数：7.10）A.YB.NC.NG(2).Synthetic biology is a very new science which has many limitations.（分数：7.10）A.YB.NC.NG(3).The goal of synthetic biology is to combine engineering metho
31、ds with biology.（分数：7.10）A.YB.NC.NG(4).There are many scientists who are skilled in both biology and engineering.（分数：7.10）A.YB.NC.NG(5).According to Randy Rettberg, it is easy to_ during the competition because you know exactly why youre doing it.（分数：7.10）_(6).Many students in the IGEM competition t
32、ried to deal with problems related to bacterial_.（分数：7.10）_(7).Students from the University of Texas used the worlds first bacterial photography system to take_.（分数：7.10）_(8).Two goals of the IGEM are to help students to bridge_ and to give them_.（分数：7.10）_(9).A team from the University of Californi
33、a tried to exploit a natural method used by bacteria to_.（分数：7.10）_(10).To make a biological tallying device, the students designed a series of devices: the first device_; the second is_ and the third_.（分数：7.10）_三、Listening Comprehens(总题数：1，分数：15.00)A.The Tread Hall is on the left of a 20-storey bui
34、lding.B.The Tread Hall is on the right of a 20-storey building.C.The Tread Hall is behind a 20-storey building.D.The Tread Hall is next to a 20-storey building.A.Because the temperature can climb to 85 Fahrenheit.B.Because the temperature can climb to 95 Fahrenheit.C.Because the temperature can clim
35、b to 75 Fahrenheit.D.Because the temperature can climb to 105 Fahrenheit.A.She will not go to the park.B.She will go to the park.C.She likes to take a walk.D.She is too tired to take a walk.A.Sixteen below zero.B.Six below zero.C.Sixteen above zero.D.Six above zero.A.Because his watch has stopped.B.
36、Because his watch is slow.C.Because his watch is fast.D.Because his watch is lost.A.Winding the watch.B.Stopping the watch.C.Setting the watch by the radio.D.Asking Mary about the time.A.At 9:00.B.At 9:30.C.At 9:25.D.At 10:00.A.Professor and student.B.Doctor and patient.C.Waiter and customer.D.Clerk
37、 and customer.四、Section A(总题数：2，分数：10.00)A.They lived in caves.B.They traveled in groups.C.They had an advanced language.D.They ate mostly fruit.A.They lived in large groups.B.They used sand as insulation.C.They kept fires burning constantly.D.They faced their homes toward the south.A.Meet his anthr
38、opology teacher.B.Lend him her magazine when shes done with it.C.Come over to his house after class.D.Help him study for an anthropology test.A.To choose a topic for a term paper.B.To type some research materials.C.To find material not available at the main library.D.To learn to use the computers th
39、ere.A.An analysis of early presidential elections.B.A comparison of political journals.C.The use of computers in calculating election results.D.The impact of television on recent presidential elections.A.It is quite general.B.Most of the information he needs will be found in newspapers,C.She thinks
40、he should change it.D.It should take a very short time to find material on it.五、Section B(总题数：3，分数：30.00)A.Family phone numbers.B.Government service phone numbers.C.Business phone numbers.D.Professional services phone numbers.A.People can call you back if necessary.B.You can dial a special number fr
41、ee.C.You dont need to pay for long distance call.D.You can get a credit coupon when you give the phone number.A.He will find out the right number for you.B.He will charge you less for the wrong number.C.He will charge you no money for the wrong number.D.He will tell you what the wrong number is.A.Fo
42、r the completion of required assignments.B.For passing given examinations.C.For the good of gaining knowledge.D.For the sake of high grades.A.To accomplish them mainly through their own efforts.B.To complete them with the aid of their tutors.C.To read all the reference books assigned by the professo
43、rs.D.To get over all the periodicals, articles and books in the library.A.Consult him outside of class.B.Look for him in the office.C.Talk to him during classroom hours.D.Make an appointment with him.A.Because he wanted to steal a violin and take it out with him.B.Because he was planning to commit a
44、 crime.C.Because he was going to earn money by playing his violin in the street.D.Because he was going to return home.A.He stood in the middle of the payment.B.He stood under a bridge near the station.C.He stood on a bridge near the station.D.He stood in front of the station.A.He was full of confide
45、nce at his success.B.He felt like a circus performer.C.He felt as if he had been performing all his life.D.He was determined to travel round the world.六、Section C(总题数：1，分数：10.00)Drunken drivingsometimes called Americas socially accepted form of murderhas become a national epidemic. Every hour of eve
46、ry day about three Americans on (36) 1 are killed by drunken drivers, adding up to an (37) 2250,000 over the past decade. A drunken driver is usually defined as one with a 0. 10 blood alcohol content or (38) 3three beers, glasses of wine or shots of whisky drunk within two hours. Heavy drinking used
47、 to be an acceptable part of the American man (39) 4 and judges were tolerant in most courts, but the drunken (40) 5has recently caused so many well-publicized (41) 6, especially involving, young children, that public opinion is no longer so tolerant. Twenty states have raised the legal drinking age to 21, (42) 7a trend in the 1960s to reduce it to 18. After New Jersey lowered it to 18, the number of people killed 18-to 20-year-old driv
