1、大学英语四级模拟试卷 700及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a short essay entitled aging of the population. You should write at least 150 words following the outline given below. 1我国人口老龄化现象日趋明显 2人口老龄化带来的问 题 3如何妥善解决人口老龄化问题 二、 Part II Reading Comprehension
2、(Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-7, mark： Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement
3、 contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 The Human Brain The brain is the most complex organ in human body. It produces our every thought, action, memory, feeling and experience of the world. This jelly-like mass of tissu
4、e, weighing in around 1.4 kilograms, contains a staggering one hundred billion nerve cells, or neurons (神经元 ). The complexity of the connectivity between these cells is mind-boggling (令人难以置信的 ). Each neuron can make contact with thousands or even tens of thousands of others, via tiny structures call
5、ed synapses (突触 ) . Our brains form a million new connections for every second of our lives. The pattern and strength of the connections is constantly changing and no two brains are alike. It is in these changing connections that memories are stored, habits learned and personalities shaped, by reinf
6、orcing certain patterns of brain activities, and losing others. Grey Matter and White Matter While people often speak of their “grey matter“, the brain also contains white matter. The grey matter is the cell bodies of the neurons, while the white matter is the branching network of thread-like tendri
7、ls called dendrites and axons that spread out from the cell bodies to connect to other neurons. But the brain also has another, even more numerous type of cell, called glial (神经胶质的 ) ceils. These outnumber neurons over ten times. Once thought to be support cells, they are now known to amplify neural
8、 signals and to be as important as neurons in mental calculations. There are many different types of neuron, only one of which is unique to humans and the other great apes, the so-called spindle cells. Brain structure is shaped partly by genes, but largely by experience. Only recently it was discove
9、red that new brain cells are being born throughout our lives a process called neurogenesis. The brain has bursts of growth and then periods of consolidation, when excess connections are removed. The most notable bursts are in the first two or three years of life. during puberty, and also a final bur
10、st in young adulthood. How a brain ages also depends on genes and lifestyle too. Exercising the brain and giving it the right diet can be just as important as it is for the rest of the body. Chemical Messengers The neurons in our brains communicate in a variety of ways. Signals pass between them by
11、the release and capture of neurotransmitter and neuromodulator chemicals, such as glutamate, dopamine, acetylcholine, noradrenalin, serotonin and endorphins. Some neurochemicals work in the synapse, passing specific messages from release sites to collection sites, called receptors. Others also sprea
12、d their influence more widely, like a radio signal, making whole brain regions more or less sensitive. These neurochemicals are so important that deficiencies in them are linked to certain diseases, For example, a loss of dopamine in the basal ganglia (神经中枢 ), which controls movements, leads to Park
13、insons disease. It can also increase susceptibility to addiction because it mediates our sensations of reward and pleasure. Similarly, a deficiency in serotonin, used by regions involved in emotion, can be linked to depression or mood disorders, and the loss of acetylcholine in the cerebral cortex (
14、大脑皮层 ) is characteristic of Alzheimers disease. Brain Scanning Within individual neurons, signals are formed by electrochemical pulses. Collectively, this electrical activity can be detected outside the scalp by an electroencephalogram (EEG). These signals have wave-like patterns, which scientists c
15、lassify from alpha (common while we are relaxing or sleeping),through to gamma (active thought). When this activity goes awry (错误的 ), it is called a seizure. Some researchers think that synchronising the activity in different brain regions is important in perception. Other ways of imaging brain acti
16、vity are indirect Functional magnetic resonance imaging (fMRI) or positron emission tomography (PET) monitors blood flow. MRI scans, computed tomography (CT) scans and diffusion tensor images (DTI) use the magnetic signatures of different tissues, X-ray absorption, or the movement of water molecules
17、 in those tissues, to image the brain. These scanning techniques have revealed which parts of the brain are associated with which functions. Examples include activities related to sensations, movement, libido, choices, regrets, motivations and even racism. However, some experts argue that we put too
18、 much trust in these results and that they raise privacy issues. Before scanning techniques were common, researchers relied on patients with brain damage caused by strokes, head injuries or illnesses, to determine which brain areas are required for certain functions. Some Structures in Mind The most
19、 obvious anatomical feature of our brains is the undulating surface of the cerebrum (大脑 ) the deep clefts are known as sulci and its folds are gyri. The cerebrum is the largest part of our brain and is largely made up of the two cerebral hemispheres. It is the most evolutionarily recent brain struct
20、ure, dealing with more complex cognitive brain activities it is often said that the right hemisphere is more creative and emotional while the left deals with logic, but the reality is more complex. Nonetheless, the sides do have some specialization, with the left dealing with speech and language, th
21、e right with spatial and body awareness. Behind the ears and temples lie the temporal lobes (颞叶 ), dealing with sound and speech comprehension and some aspects of memory. And to the fore are the frontal and prefrontal lobes (额和额前叶 ), often considered the most highly developed and most “human“ of reg
22、ions, dealing with the most complex thought, decision making, planning, conceptualizing, attention control and working memory. They also deal with complex social emotions such as regret, morality and empathy. Another way to classify the regions is as sensory cortex and motor cortex, controlling inco
23、ming information, and outgoing behavior respectively. Below the cerebral hemispheres, but still referred to as part of the forebrain, is the cingulated (扣带 ) cortex, which deals with directing behavior and pain. And beneath this lies the corpus callosum, which connects the two sides of the brain. Ot
24、her important areas of the forebrain are the basal ganglia, responsible for movement, motivation and reward. The back of the brain has a highly convoluted and folded swelling called the cerebellum, which stores patterns of movement, habits and repeated tasks things we can do without thinking about t
25、hem. The most primitive parts, the midbrain and brain stem, control the bodily functions we have no conscious control of, such as breathing, heart rate, blood pressure, sleep patterns, and so on. They also control signals that pass between the brain and the rest of the body, through the spinal cord.
26、 2 Where are memories stbred? （ A） In the nerve cell bodies. （ B） In the synapses. （ C） In neuron connections. （ D） In connection patterns. 3 What do we know about glial ceils? （ A） They are much more than neurons. （ B） They are only support cells. （ C） They send neural signals. （ D） They are unique
27、 to humans. 4 Neurogenesis occurs_. （ A） in our whole life （ B） when excess connections are pruned （ C） in three short periods （ D） when the brain is exercised 5 How do the neurons in our brains communicate with each other? （ A） They communicate by linking to the basal ganglia. （ B） They work in the
28、 synapse to pass messages. （ C） They spread their influence like a radio signal. （ D） They release and capture neurochemicals. 6 What do we know about the brain scanning technology according to the passage? （ A） EEG is a direct way, and fMRI, MRI, CT and DTI are indirect. （ B） EEG and fMRI are direc
29、t ways, and fMRI, CT, and DTI are indirect. （ C） EEG, fMRI, MRI, CT and DTI are all indirect ways. （ D） EEG, fMRI, MRI, CT and DTI are all direct ways. 7 How did researchers find functions of the brain parts when scanning techniques were uncommon? （ A） They measured temperatures of different areas o
30、f the scalp （ B） They used drugs to control different parts of the brain. （ C） They studied patients who had brain damage. （ D） They studied other great apes to make guesses. 8 The right hemisphere of the cerebrum_. （ A） has a more undulating surface than the left （ B） is more evolutionarily advance
31、d than the left. （ C） deals with logic and language （ D） deals with spatial and body awareness 9 We often consider_as more advanced than other parts of the brain. 10 The corpus callosum lies beneath_. 11 Breathing and heart rate are controlled by_. Section A Directions: In this section, you will hea
32、r 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices ma
33、rked A, B, C and D, and decide which is the best answer. （ A） She runs a high fever. （ B） She suffers from heart-disease. （ C） She has a terrible headache. （ D） She catches no disease at all. （ A） Fashion. （ B） Style. （ C） Beauty. （ D） Comfort. （ A） To invite the man to join them. （ B） To ask him to
34、 help cook. （ C） To suggest politely that he leave. （ D） To encourage him to have another drink. （ A） The shops are not crowded in December. （ B） Many people go shopping despite the cold weather in December. （ C） People dont like to do shopping in busy shops in winter. （ D） In December people stay a
35、t home because of the cold weather. （ A） She is typing. （ B） She is playing the piano. （ C） She is taking a picture. （ D） She is baking bread. （ A） A retailer. （ B） An electrician. （ C） A salesman. （ D） An operator. （ A） Steven has found a job as an actor. （ B） Stevens behavior may cause his loss of
36、 the job. （ C） Steven has been in his position for quite a long time. （ D） Stevens job as a manager is difficult. （ A） The suburbs. （ B） Downtown. （ C） Both downtown and suburbs. （ D） Neither downtown nor suburbs. （ A） She does not have enough money. （ B） She cares more about her inner beauty. （ C）
37、She does like to follow suit. （ D） She does not believe in the cosmetic surgery. （ A） She is still slim in her late 50s. （ B） She is short and unconfident. （ C） She has no good figure but is quite intelligent. （ D） She likes joking about her body and looks. （ A） The influence from the media. （ B） Th
38、e pressure from the society. （ C） The popularity of the external beauty. （ D） The influence of commodity economy. （ A） At a television studio. （ B） On a radio program. （ C） In a job interview. （ D） In a factory. （ A） He thinks people are more likely to buy music than books. （ B） He believes that the
39、re is a demand for books on music. （ C） He thinks that there isnt much future for e-books. （ D） He thinks that there is a good chance that the business will develop. （ A） She seems rather sympathetic. （ B） She appears rude. （ C） She seems to be a little doubtful. （ D） She appears to find them very i
40、nteresting. （ A） To boost book sales. （ B） To encourage publishers to publish e-books. （ C） To advertise their machine. （ D） In order to advertise their software. Section B Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the
41、 passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D. （ A） Express it openly in a calm reasonable way. （ B） Burst with anger, scream and yell. （ C） Keep it inside. （ D） Cry. （ A） Heart disease. （ B）
42、 High blood pressure. （ C） Cancer. （ D） Diabetes. （ A） You shouldnt express your anger while angry and youd better wait until it has cooled down. （ B） Keeping anger inside may lead to high blood pressure. （ C） Repressing anger is more dangerous to your health than expressing it. （ D） Expressing ange
43、r is never dangerous to your health. （ A） Before the Civil War. （ B） After the Civil War. （ C） During the Civil War. （ D） Thirty years ago. （ A） Milk cows. （ B） Build the barn. （ C） Cut wood. （ D） Harvest crops. （ A） Jim joined the army after leaving the farm. （ B） James A. Garfield was Jims idol. （
44、 C） Taylor must regret refusing Jim. （ D） Taylor suffered a crop failure. （ A） About 3000 years ago. （ B） About 1300 years ago. （ C） About 4000 years ago. （ D） Not known. （ A） Two hours. （ B） Half an hour. （ C） One hour. （ D） Three hours. （ A） People were not so worried about the exact time. （ B） Pe
45、ople didnt know how to make them. （ C） The king didnt want it. （ D） There was no plane or train at that time. （ A） Answer phone calls. （ B） Say your name. （ C） Start a small machine. （ D） Cook different food. Section C Directions: In this section, you will hear a passage three times. When the passag
46、e is read for the first time, you should listen carefully for its general idea. When the passage is read for the second time, you are required to fill in the blanks numbered from 36 to 43 with the exact words you have just heard. For blanks numbered from 44 to 46 you are required to fill in the miss
47、ing information. For these blanks, you can either use the exact words you have just heard or write down the 36 I have learned, often the hard way, that there are a few simple rules about how to make life easier both before and after your 【 B1】 _. First of all, always check and double-check 【 B2】 _ti
48、mes. It is 【 B3】 _how few people really do this carefully. Once I arrived at the airport a few minutes after ten. My 【 B4】 _had got the ticket for me and I thought she had said that the plane left at 10:50. I walked 【 B5】_to the departure desk, thinking I still had a little time to 【 B6】 _. I hadnt
49、bothered to take a good look at the ticket. The clerk at the desk told me politely but 【 B7】 _that the departure time was 10:15 and that the flight was, according to international 【 B8】 _, “now closed“. I had to wait three hours for the next one and missed an important meeting. The important rule is to remember that even in this age of credit cards, it is still important to 【 B9】 _. A few years ago I was sent to Tulsa, Oklahoma. I flew there from London via Dall
