Most of the time, the ground feels solid beneath our feet.That's comforting. But it's also misleading because there's actually a lot going on underground. Masses of land (called plates) slip, slide, and bump against each other, slowly changing the shape of continents and oceans over millions and billions of years.
Scientists know that Earth formed about 4.5 billion years ago. They also know that our planet was hot at first. As it cooled, its outermost layer, called the crust, eventually formed moving plates. Exactly when this shift happened, however, is an open question.
Now, an international group of researchers has an answer. They've found new evidence suggesting that Earth's crust started shifting at least 3.8 billion years ago. The new estimate is 1.3 billion years earlier than previous ones.
Not long before 3.8 billion years ago, lots of asteroids were pummeling Earth, keeping its crust in a hot, molten state. After the hard crust formed, much of it sank at various times into the planet's hot insides. There, it melted before returning to the surface as lava.
In some places, however, the crust never sank. One of the oldest such places is in Greenland, in an area called the Isua supracrustal(上地壳) belt. The rocky crust there is between 3.7 and 3.8 billion years old. The belt was once part of the seafloor, but now it is exposed to air.
The researchers recently look at the Isua supracrustal belt. They noticed long, parallel cracks in the rock that have been filled in with a type of volcanic rock.
To explain this structure, the scientists propose that tension in the crust caused the seafloor to crack open long ago. Hot, liquid rock, called magma(岩浆), flowed up slowly from deep inside Earth to fill the cracks. Finally, the area cooled, forming what we see today.
That explanation, plus chemical clues inside the rock, suggests that the Isua supracrustal belt was once part of a plate under tne ocean, beginning around 3.8 billion years ago.
16. The ground beneath our feet is indeed still.
A.right B. wrong C. not mention
17.The shape of lands and oceans are slowly changed with the movements of plates.
A.right B. wrong C. not mention
18. Earth cooled down shortly after it was formed.
A.right B. wrong C. not mention
19.Scientists once estimated that Earth’s crust started shifting three billion years ago.
A.right B. wrong C. not mention
20.It took a long time for the melted crust to become hard.
A. right B. wrong C. not mention
21.The formation of the Isua supracrustal belt is thought to have started about 3.8 billion years ago.
A.right B. wrong C. not mention
22. The lsua supracrustal belt is now a popular holiday resort.
1. The iPad is a tablet computer（平板电脑）designed, developed and marketed by Apple. It is particularly marketed as a platform for audio and visual media such as books, periodicals(期刊), movies, music, and games, as well as web content. At about 1.5 pounds (680grams), its size and weight are between those of most contemporary smartphones and laptop computers. Apple released the iPad in April 2010, and sold 3 million of the devices in 80 days.
2． The iPad runs the same operating system as the iPod Touch and iPhone. It can run its own applications as well as ones developed for iPhone. Without modification, it will only run programs approved by Apple and distributed via its online store.
3. Like iPhone and iPod Touch, the iPad is controlled by a multitouch display—a break from most previous tablet computers, which uses a pressure-triggered stylus（触控笔）. The iPad uses a Wi-Fi data connection to browse（浏览） the Internet, load and stream media, and install software. Some models also have a 3G wireless data connection which can connect to GSM 3G data networks. The device is managed and synchronized（同步） by iTunes on a personal computer via USB cable.
4. An iPad has different features and applications one can use to execute different and interesting things. There are lots of iPad applications that the owner can use to enhance the way they communicate. Some of these are how to use social networking sites and other online options. one of the most common uses is for e-mails services. iPad applications like Markdown Mail allow the adoption of specific and particular options. They enable the owner to personalize their email accounts.
5. While the iPad is mostly used by consumers it also has been taken up by business users. Some companies are adopting iPads in their business offices by distributing or making available iPads to employees. Examples of uses in the workplace include lawyers responding to clients, medical professionals accessing health records during patient exams, and managers approving employee requests. A survey by Frost Sullivan shows that iPad usage in office workplaces is linked to the goals of increased employee productivity, reduced paperwork, and increased revenue.
23. Paragraph 2 ____
24. Paragraph 3 ____
25. Paragraph 4 ____
26. Paragraph 5 ____
A. Business Usage.
B. Display and Data Connection.
C. Feature and Application.
D. Difference from iPhone.
E. Operating System.
F. Online Stores.
27. In April 2010 the iPad developed by Apple was_____
28. The iPad will only run programs approved by Apple if not _____
29. iPad applications enable the owner's email accounts to be _____
30. iPad uses in offices enable employee productivity to be ____
When you think about math, you probably don't think about breaking the law, solving mysteries or finding criminals. But a mathematician in Maryland does, and he has come up with mathematical tools to help police find criminals.
People who solve crimes look for patterns that might reveal （揭示） the identity of the criminal. It's long been believed, for example, that criminals will break the law closer to where they live, simply because it's easier to get around in their own neighborhood. If police see a pattern of robberies in a certain area, they may look for a suspect who lives near the crime scenes. So, the farther away from the area a crime takes place, the less likely it is that the same criminal did it.
But Mike O'Leary, a mathematician at Towson University in Maryland, says that this kind of approach may be too simple. He says that police may get better clues to the location of a criminal's home base by combining these patterns with a city's layout （布局） and historical crime records.
The records of past crimes contain geographical information and can reveal easy targets - that is, the kind of stores that might be less difficult to rob. Because these stores are along roads, the locations of past crimes contain information about where major streets and intersections are. O'Leary is writing a new computer program that will quickly provide this kind of information for a given city. His program also includes information about the people who live in the city, and information about how a criminal's patterns change with age. It's been shown, for example, that the younger the criminal, the closer to home the crime.
Other computer programmers have worked on similar software, but O'Leary's uses more math. The mathematician plans to make his computer program available, free of charge, to police departments around the country.
The program is just one way to use math to fight crime. O'Leary says that criminology - the study of crime and criminals - contains a lot of good math problems. "I feel like I'm in a gold mine and I'm the only one who knows what gold looks like," he says. "It's a lot of fun."
31. Which of the following statements about math is true?
A. It is too difficult for the police to use in finding criminals.
B. Few people associate it with finding criminals.
C. Some criminals make use of it when committing crimes.
D. it has long been employed in solving crimes.
32. People tend to think there is a relationship between
A. the time of a crime and the age of the criminal.
B. the type of a crime and the identity of the criminal.
C. the pattern of a crime and the equipment of the criminal.
D. the location of a crime and the residence of the criminal.
33. O’Leary includes all the following information in writing his program EXCEPT
A. the records of past crimes.
B. the locations of police bureaus.
C. the people living in the city.
D. the change of a criminal’s patterns with age.
34. O’Leary’s program is different from other similar software in that
A. it is inexpensive.
B. it is more user-friendly.
C. it uses more math.
D. it is available all over the world.
35. It can be inferred from the last paragraph that O’Leary
A. will develop programs for other governmental departments.
B. is going to use math in looking for gold.
C. thinks it’s interesting to learn math.
D. will further use math in studying crimes and criminals.
Some People Do Not Taste Salt Like Others
Low-salt foods may be harder for some people to like than others, according to a study by a Penn State College of Agricultural Sciences1 food scientist. The research indicates that genetic factors influence some of the difference in the levels of salt we like to eat.
Those conclusions are important because recent, well-publicized efforts to reduce the salt content in food2 have left many people struggling to accept fare that simply does not taste as good to them as it does to others3, pointed out John Hayes, assistant professor of food science, who was lead investigator? on the study.
Diets high in salt can increase the risk of high blood pressure and stroke. That is why public health experts and food companies are Working together on ways to help consumers lower salt intake through foods that are enjoyable to eat. This study increases understanding of salt preference and consumption.
The research involved 87 carefully screened participants who sampled salty foods such as soup and chips, on multiple occasions, spread out over weeks5. Test subjects were 45 men and 42 women, reportedly healthy, ranging in age from 20 to 40 years. The sample was composed of individuals who were not actively modifying their dietary intake and did not smoke cigarettes. They rated the intensity of taste on a commonly used scientific scale, ranging from barely detectable to strongest sensation of any kind.
"Most of us like the taste of salt. However, some individuals eat more salt, both because they like the taste of saltiness more, and also because it is needed to block other unpleasant tastes in food," said Hayes. "Supertasters, people who experience tastes more tensely, consume more salt than nontasters do. Snack foods have saltiness as their primary flavor, and at least for these foods, more is better, so the supertasters seem to like them more. "
However, supertasters also need higher levels of salt to block unpleasant bitter tastes in foods such as cheese, Hayes noted. "For example, cheese is a wonderful blend of dairy flavors from fermented, milk, but also bitter tastes from ripening that are blocked by salt," he said. "A supertaster finds low-salt cheese unpleasant because the bitterness is too pronounced6.
Hayes cited research done more than 75 years ago by a chemist named Fox and a geneticist named Blakeslee, showing that individuals differ in their ability to taste certain chemicals. As a result, Hayes explained, we know that a wide range in taste acuity exists, and this variation is as normal as variations in eye and hair color.
"Some people, called supertasters, describe bitter compounds as being extremely bitter, while others, called nontasters, find these same bitter compounds to be tasteless or only weary bitter," he said. "Response to bitter compounds is one of many ways to identify biological differences in food preference because supertasting7 is not limited to bitterness.
36. John Hayes pointed out that __________.
A. food with less salt tastes better.
B. many people make efforts to accept low-salt food.
C. many people never eat low-salt food.
D. it is good to health to eat food without salt.
37. The fourth paragraph briefly describes______?
A. how the subjects were selected and what they were asked to do.
B. why the number of subjects was limited to 87.
C. why more male subjects were chosen than female ones.
D. how salty foods were made and distributed to the subjects in the research.
38. It is true that ________.
A. nontasters like to share salty cheese with supertasters.
B. nontasters consume more salt because they like intense tastes.
C. supertasters like the taste of saltiness to block sweet tastes in food.
D. supertasters like snack foods more as they contain higher levels of saltiness.
39. Supertasters prefer high-salt cheese because ________.
A. it is good to health.
B. it is rich in nutrition.
C. it has intense bitter tastes.
D. it tastes less bitter.
40. It can be inferred from the last paragraph that taste acuity is ________.
A. identified with certain chemicals.
B. developed over time after birth.
C. related to one’s eye and hair color.
D. genetically determined.
Cell phone: Hang up or Keep Talking
Millions of people are using cell phones today. In many places it is actually considered unusual not to use one. In many countries, cell phones are very popular with young people. They find that the phones are more than a means of communication-having a mobile phone shows that they are cool and connected
The explosion around the world in mobile phone use has some health professional worried... Some doctors are concerned that in the future many people may suffer health problems from the use of mobile phones.. In England, there has been a serious debate about this issue... Mobile phone companies are worried about the negative publicity of such ideas.. They say that there is no proof that mobile phones are bad ...for health
On the other hand, why do some medical studies show changes in the brain cells of some people who use mobile phones? Signs of change in the tissues of the brain and head can be detected with modern scanning equipment.. In one case a traveling salesman had to retire at a young age because of serious memory loss.. He couldn't remember even simple tasks. He would often forget the name of his own son.. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years... His family doctor blamed his mobile phone use, but his employer's doctor didn't agree...
What is it that makes mobile phones potentially harmful? The answer is radiation.. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.
As the discussion about their safety continues, it appears that it's best to use mobile phones less often.. Use your regular phone if you want to talk for a long time. Use your mobile phone when you really need it.. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says that they are bad for health. So for now, it's wise not to use your mobile phone too often.
41. People buy cell phones for the following reasons EXCEPT that
A. they’re popular.
B. they’re useful.
C. they’re cheap.
D. they’re convenient.
42. The word "detected" in paragraph 3 could be best replaced by
43. The salesman retired young because
A. he couldn’t remember simple tasks.
B. he disliked using mobile phones.
C. he was tired of talking on his mobile phone.
D. his employer’s doctor persuaded him to.
44. On the safety issue of mobile phones， the manufacturing companies
A. deny the existence of mobile phone radiation.
B. develop new technology to reduce mobile phone radiation.
C. hold that the amount of radiation is too small to worry about.
D. try to prove that mobile phones are not harmful to health.
45. The writer’s purpose of writing this article is to advise people
The coast of the State of Maine is one of the most irregular in the world. A straight line running from the southernmost coastal city to the northernmost coastal city would measure about 225 miles. If you followed the coastline between these points, you would travel more than ten times as far. This irregularity is the result of what is called a drowned coastline.______ (46). At that time, the whole area that is now Maine was part of a mountain range that towered above the sea. As the glacier(冰川)descended, however, it expended enormous force on those mountain, and they sank into the sea.
As the mountain sank, ocean water charged over the lowest parts of the remaining land, forming a series of twisting inlets and lagoons(咸水湖). The highest parts of the former mountain range, nearest the shore., remained as the island. ______ (47) Marine fossils found here were 225 feet above sea level, indicating the level of the shoreline prior to the glacier.
The 2500-miles-long rocky coastline of Maine keeps watch over nearly two thousand island. Many of these islands are tiny and uninhabited, but many are home to thriving communities. Mt. Desert Island is one of the largest., most beautiful of the Maine coast islands. Measuring 16 miles by 12 miles, Mt. Desert was essentially formed as two distinct islands. ______ (48).
For years, Mt. Desert land, particularly its major settlement, Bar Harbor, afforded summer homes for the wealthy, Recently though, Bar Harbor has become a rapidly growing arts community as well. But, the best part of the island is the unspoiled forest land known as Acadia National Park. Because the island sits on the boundary line between the temperate (温带) and sub-Arctic zones, the island supports the plants and animals of both zones as well as beach, inland, and alpine(高山的) plants,_______(49) The establishment of Acadia National Park in 1916 means that this natural reserve will be perpetually available to all people, not just the wealthy. Visitors to Acadia may receive nature instruction from the park naturalists as well as enjoy camping, cycling, and boating. Or they may choose to spend time at the archeological museum, learning about the Stone Age inhabitants of the island.
The best view on Mt. Desert land is from the top of Cadillac Mountain._______(50)From the summit, you can gaze back toward the mainland or out over the Atlantic Ocean and contemplate the beauty created by a retreating .
A.The term comes from the activity of the ice age.
B. It also lies in a major bird migration lane and is a resting sport for many birds.
C. This mountain rises 1,532 feet, making it the highest mountain on the Atlantic seaboard.
D. The wealthy residents of Mt. Desert Island selfishly kept it to themselves.
E. It is spilt almost in half by Some Sound, a deep and narrow stretch of water, seven miles long.
F. Mt. Desert Island is one of the most famous of all the island left behind by the glacier.
Young Adults Who Exercise Get Higher IQ Scores
Young adults who are fit have a higher IQ and are more likely to go on to university, reveals a major new study __51__ at the Sahlgrenska Academy and Sahlgrenska University Hospital.
The results were recently published in the Proceedings of the National Academy of Sciences (PNAS). The study _52___ 1.2 million Swedish men doing military service who were born between 1950 and 1976. The research group analyses the __53__ of both physical and IQ tests the youngsters took right after they started serving the army.
The study shows a clear link _54__ good physical fitnes and better results for the IQ test. The strongest links are for _55__ thinking and verbal comprehension. But it is only fitness that plays a _56__ in the results for the IQ test, and not strength. “Being fit means that you also have good heart and lung _57__ and that your brain gets plenty of oxygen.” says Michael Nilsson, professor at the Sahlgrenska Academy and chief physician at the Sahlgrenska University Hospital. “This may be one of the reasons why we can see a clear link with fitness, but not with muscular _58__. We are also seeing that there are growth factors that are important.”
By analyzing data for twins, the researchers have been _59__ to determine that it is primarily environmental factors and not genes that _60__ the link between fitness and a higher IQ.
“We have also shown that those youngsters who _61__ their physical fitness between the ages of 15 and 18 increase their cognitive performance,” says Maria Aberg, researcher at the Sahlgrenska Academy and physician at Aby health centre. “This being the case, physical education is a _62___ that has an important place in schools, and is an absolute must _63___ we want to do well in maths and other theoretical subjects.”
The researchers have also compared the results from fitness tests during national service _64___ the socio-economic status of the men later in life. Those who were fit at 18 were more _65___ to go into higher education, and many secured more qualified jobs.
51.A. put B. carried C. cut D. taken
52.A. kept B. involved C. found D. helped
53.A. answers B. questions C. standards D. results
54.A. among B. behind C. between D. inside
55.A. imaginary B. typical C. positive D. logical
56.A. game B. place C. role D. trick
57.A. shape B. capacity C. disease D. treatment
58.A. exercise B. training C. movement D. strength