Caffeine not only gives us a daily jump start, but new research suggests it also can strengthen long-term memory.
According to the US Food and Drug Administration, nearly 90 percent of people worldwide consume about 200 milligrams of caffeine each day. That' s equivalent to about one strong cup of coffee a day. Writing in " Nature Neuroscience" , Johns Hopkins University researchers say their findings show that caffeine strengthens certain memories for up to 24 hours after being taken in.
" We've always known that caffeine has cognitive-enhancing effects (促智效果) , but its particular effects on strengthening memories and making them resistant to forgetting has never been examined in detail in humans, " said senior author of the paper Michael Yassa. " We re- port for the first time a specific effect of caffeine on reducing forgetting over 24 hours. " Conducting a double-blind trial, the researchers worked with a test group of people who didn't regularly consume caffeinated products. Five minutes after studying a series of images, the test subjects were given either a placebo(无效对照剂) or a 200-milligram caffeine tablet.
To check the caffeine levels of their test subjects, the research team took saliva samples (唾液样品) from them before they took their tablets and again one, three and 24 hours afterwards.
Both groups of test participants ( those who took the placebo and those who took the caffeine tablet) were tested the following day to see if they could recognize the images they' d seen the previous day.
The test included showing the test subjects another series of images that included some new images , those that were shown the previous day, as well as other images that were similar, but not the same as those they had viewed earlier.
The researchers found that more members of the group who were given the caffeine tablets were able to correctly identify some of the new images as " similar" to previously viewed images rather than incorrectly identifying them as the same.
"We also know that caffeine is associated with health and longevity(长寿) and may have some protective effects from cognitive decline like Alzheimer' s disease (阿尔茨海默症). " said Yassa.
The purpose of the new research is ____________.
| A．to examine caffeine ' s memory-strengthening effects in detail |
| B．to write the paper " Nature Neuroscience" |
| C．to prove caffeine has cognitive-enhancing effects |
| D．to survey how much caffeine people consume a day |
During the research , the researchers did the following things EXCEPT ________.
| A．giving the test subjects placebos or caffeine tablets |
| B．checking the caffeine levels of the test subjects |
| C．showing the test subjects series of images |
| D．encouraging the test subjects to drink more coffee |
How did the test subjects show the caffeine ' s memory-strengthening effects?
| A．By taking the caffeine tablets instead of placebos. |
| B．By recognizing images they ' d seen the previous day. |
| C．By identifying the new images as the same. |
| D．By telling the differences between new images. |
What will the next part of the text possibly talk about?
| A．Ways to achieve health and longevity. |
| B．The harmful effects of cognitive decline. |
| C．The treatment for Alzheimer' s disease. |
| D．The effects caffeine has on health. |
To extinguish (熄灭) different kinds of fires, several types of fire extinguishers have been invented. They must be ready for immediate use when fire breaks out. Most portable (手提式的) kinds operate for less than a minute, so they are useful only on small fires. The law requires ships, trains, buses and planes to carry extinguishers.
Since fuel, oxygen (氧气) and heat must be present in order for fire to exist, one or more of these things must be removed or reduced to extinguish a fire. If the heat is reduced by cooling the material below a certain temperature, the fire goes out. The cooling method is the most common way to put out a fire. Water is the best cooling material because it is low in cost and easy to get.
Another method of extinguishing fire is by cutting off the oxygen. This is usually done by covering the fire with sand, steam or some other things. A blanket may be used do cover a small fire.
A third method is called separation, which includes removing the fuel, or material easy to burn, from a fire, so that it can find no fuel.
The method that is used to put out a fire depends upon the type of fire. Fires have been grouped in three classes. Fires in wood, paper, cloth and the like are called Class A fires. These materials usually help keep the fire on. Such fires can be stopped most readily by cooling with water.If a fire breaks out on a bus, which of the follow should be ready there for you to use?
A.Sand B.Water C.A blanket. D.An extinguisher.
【 小题2】 To cover a small piece of burning wood with a basin in order to stop the fire is an example of _______.
A.separating the fire B.reducing the heat
C.removing the fuel D.cutting off the oxygenIn choosing how to put out a fire, we should first be clear about_______.
| A．when it breaks out | B．how it comes about |
| C．what kind it is | D．where it takes place |
What would the author probably discuss in the paragraph that follows?
| A．Another class of fires |
| B．Another type of extinguishers |
| C．How fires break out. |
| D．How fires can be prevented. |
A home computer not only helps children master the old ways of learning, but also opens up possibilities that simply aren’t available in traditional education. Some software, for example, allows kids to make decisions and see the results in different situations. The World Wide Web encourages young minds to move easily from link to link, topic to topic. The best software draws children into learning by making them curious—what if I click on this picture, drag this over here, visit that website?
Knowing how to use a computer also encourages a child’s confidence. Kids figure out quickly that computers are powerful, and mastering the machine makes them feel grown-up. In turn, feeling confident on a computer often translates to academic(学术的)confidence. Researchers have found that attitudes toward writing, for example, improve when students write on a computer.
Perhaps most importantly, computers can enrich family life. Forget the idea that computer kids are separated. Children like to use the computer with adults and other kids, asking questions and comparing results. “The Internet is a unique opportunity to bring resources home, ”notes Susan Haugland, PhD, Cape Girardeau, Mo. , author of Computer and Young Children:A World of Discovery.
Although the benefits of computers are real, they have disadvantages, too. Kids can lose their way, wasting hours on mindless software of violent games. Just as parents have always helped children make good choices about everything from friends to food, books to TV, now we must make sure they get the best out of computers.The passage is mainly talking about______.
| A．the disadvantages of children’s using computers |
| B．the advantages of children’ using computers |
| C．the development of computers |
| D．the fact that using computers makes children lose their way |
Which of the following is NOT an advantage of a home computer?
| A．It provides new ways of learning. |
| B．It encourages children’ confidence. |
| C．It can enrich family life. |
| D．Kids can play violent games on it. |
What effects do computers have on family life?
| A．They reduce the connection between family members. |
| B．They destroy the relationship between parents and kids. |
| C．They provide more opportunities of communication. |
| D．They make all the family members study together. |
According to the last paragraph, we can learn that we should______.
| A．let children use computers freely |
| B．forbid children to use computers in their spare time |
| C．permit children to use any software they like |
| D．help children make good use of the computers |
It is the injury from breathing cigarettes that has led to the invention of e-cigarettes. Using these cigarettes requires small power from battery and these cigarettes are also available in various flavors and varied nicotine levels. Owing to the fact that the charge from a short cable is required, carrying the electronic cigarettes can’t be that easy in some case. This means that the smoking habits of individuals are in fact controlled! Also, the human body is protected from harmful smoke that is not given off by the electrical version of these new age cigarettes.
The cigarettes are in a fine pack and they are durable(持久的)! For the first time ever, tobacco smokers do not have to carry matches and lighters which may cause burns to their finger tips and boring holes into their clothes! The result is basic dignity for the smokers because they will not disrespect the non-smokers among them by polluting the air that they breathe. Electronic cigarettes and the packages they come in can also be reused, which means that a lot of money can be saved.
They are environmentally friendly. For starters, this kind of cigarettes cannot be put on unless with a source of an electrical current. This means that rooms and pathways do not, under any circumstances, get filled with smoke just because a smoker passed by! The smoke is done away, meaning the air, even around a smoker, is always fresh! Disposals(处理) for the cigarettes have also been invented so that there are no harmful smoking bits and pieces carelessly thrown away which pollute the environment!
E-cigarettes have made the world a better place at the very least. Those who are addicted to smoking on a regular or even irregular basis can therefore do so responsibly and give better consideration to their health.It’s learned from Paragraph 1 that .
| A．the original smoking habits of smokers are hard to control |
| B．e-cigarettes have different tastes and nicotine levels |
| C．the electronic cigarettes are convenient to carry |
| D．the short cable is used to determine how fully the batteries are charged |
What’s the main idea of Paragraph 3?
| A．Why do e-cigarettes produce no smoke. |
| B．E-cigarettes are environmentally friendly. |
| C．Why are disposals for the cigarettes invented. |
| D．E-cigarettes benefit both smokers and non-smokers. |
According to the author, e-cigarettes .
| A．matter less to heavy smokers |
| B．are right alternatives to smokers |
| C．shouldn’t be overvalued |
| D．should be made cheap |
What’s the purpose of this passage?
| A．To introduce an invention. |
| B．To describe the wide spread of e-cigarettes. |
| C．To explain the injury from breathing cigarettes. |
| D．To show how to smoke e-cigarettes. |
According to sociologists(社会学家), every modern industrial society has some form of social stratification(阶层). Class, power and status are important in deciding people's rank in society.
Class means a person's economic position in society. A commonly used classification is lower class, middle class and upper class. While sociologists disagree on how these terms should be exactly defined, they do describe societies like the United States quite well. One study shows that 53% of Americans belong to the lower class, 46% the middle class, and 1% the upper class. Interestingly, a surgeon earning $500,000 a year and a bus driver earning $50,000 a year both regard themselves as the middle class!
Power refers to the amount of control a person has over other people. Obviously, people in positions of great power (such as governors) exercise(行使)big power, but people who take orders from others have less power. Power and class do not always go hand in hand, however. For example, the governor of a state has great power, but he or she may not belong to a corresponding (相应的)economic class. Generally, however, there is a relationship between power and class. To our knowledge, there aren't too many people who aren't millionaires in the U．S. Senate!
Status is the honor or respect attached to a person's position in society. It can also be affected by power and class, but not necessarily so. For example, a university professor may have a high status but not belong to a high social class or have a lot of power over others.What can we learn about “the middle class” from Paragraph 2?
| A．People earning $50,000 a year belong to the middle class. |
| B．Nearly half Americans belong to the middle class. |
| C．People generally consider bus drivers as the middle class. |
| D．Sociologists have a clear definition of the middle class. |
According to the text, we know that ________.
| A．Power and class do not always correspond with each other |
| B．Status refers to a person's economic position in society |
| C．People with high status have a lot of control over others |
| D．Class is less important in deciding a person's social rank |
Which of the following shows the structure of the whole text?
China is a land of bicycles. At least it was back in 1992 when I traveled the country. Back then everyone seemed to be riding a bicycle. Millions of them, all black. Cars were rare. Yet since my arrival in Beijing last year, I've found the opposite is true. There are millions of cars. However, people still use their bicycles to get around. For many, it's the easiest and cheapest way to travel today. Bicycles also come in different colors—silver, green, red, blue, yellow, whatever you want.
It's fun watching people biking. They rush quickly through crossroads, move skillfully through traffic, and ride even on sidewalks(人行道). Bicycles allow people the freedom to move about that cars just can't provide.
Eager to be part of this aspect of Chinese culture, I decided to buy a bicycle. Great weather accompanied my great buy. I immediately jumped up on my bicycle seat and started home.
My first ride home was orderly(守秩序的). To be safe, I stayed with a “pack” of bikers while cars on the streets came running swiftly out of nowhere at times. I didn't want to get hit. So I took the ride carefully.
Crossing the streets was the biggest problem. It was a lot like crossing a major highway back in the United States. The streets here were wide, so crossing took time, skill and a little bit of luck.
I finally made it home. The feeling on the bicycle was amazing. The air hitting my face and going through my hair was wonderful. I was sitting on top of the world as I passed by places and people. Biking made me feel alive.According to the author, why are bicycles still popular in China today?
| A．Because they are traditional and safe. |
| B．Because they are convenient and inexpensive. |
| C．Because they are colorful and available. |
| D．Because they are fast and environment friendly. |
The author decided to buy a bicycle because he intended ________.
| A．to ride it for fun |
| B．to use it for transport |
| C．to experience local culture |
| D．to improve his riding skills |
How did the author feel about his street crossing?
| A．It was boring. | B．It was difficult. |
| C．It was lively. | D．It was wonderful. |
Which of the following best describes the author's biking experience?
| A．The author enjoyed showing off his biking skills. |
| B．The author was annoyed by the air while riding. |
| C．The author was praised by the other bikers. |
| D．The author took great pleasure in biking. |
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