A new study says one part of the human brain may become smaller as the result of a condition known as jet lag. Jet lag results from flying long distances in an airplane. People with jet lag may feel extremely tired for several days. They may also have problems thinking clearly and remembering.

Recently a researcher at the University of Bristol in Britain reported the findings of his jet lag study, which involved twenty young women who worked for international airlines. They had served passengers on airplanes for five years. These flight attendants flew across many countries and at least seven time zones. In the study, the flight attendants had different amounts of time to recover from jet lag. Half the women spent five days or fewer in their home areas between long flights The other half spent more than fourteen days in their home areas.

The researcher took some saliva from the women's mouths to measure levels of a hormone(荷尔蒙) that increases during stress (紧张). He tested them to see if they could remember where black spots appeared on a computer screen. And he took pictures of their brains to measure the size of the brain's temporal lobes (脑叶).

It was found that the women who had less time between flights had smaller right temporal lobes. This area of the brain deals with recognizing and remembering what is seen. The same group performed worse and had slower reaction times on the visual memory test. And their saliva samples showed higher levels of stress hormones.

The researcher believes the brain needs at least ten days to recover after a long trip. He says airline workers told him their ability to remember got worse after working on planes for about four years. Other studies have shown that increased feelings of stress can cause a loss of cells in the part of the brain that controls memory.

Scientists say more tests are needed to study the effects of jet lag on the brain. They want to find out if too much jet lag could permanently (永久性的) affect memory.

According to the text, jet lag _________.

A. can cause difficulties in speaking

B. can make people feel tired for a few weeks

C. can be only found in flight attendants

D. can be caused by flying over several time zones

It can be inferred from the text that _________.

A. the conclusion is refused by many scientists

B. scientists fear that this research is not done properly

C. every scientific conclusion needs the support from many tests

D. the women who were examined in the research were not healthy

From the result of the research we can see that _________.

A. the women who have longer rest at home show better memory

B. the women who fly in short time have smaller right temporal lobes

C. the women who have longer flights fail the memory test

D. the women who rest more than 14 days produce less hormones

What is the subject discussed in the text?

A. The cause of jet lag.      B. A story of a group of flight attendants.

C. The importance of having enough rest after flights.

D. A research about the effects of jet lag on the brain.

A dam is a man-made structure built across a river. Most dams are built to control a river’s water flow, improve navigation and control flooding. However, some dams are built to produce hydro-electric power.

Hydro-electric power is produced as water passes through a dam, and into a river below. The more water that passes through a dam, the more energy is produced. Once a dam is built, a man-made lake is created behind the dam.

Electricity is produced by a kind of equipment called a turbine(水轮机). Turbines contain metal coils(线圈) surrounded by magnets(磁铁). When the magnets move round rapidly over the metal coils, electricity is produced. Turbines are located inside dams. The falling water makes the magnets go around the coils.

Dams provide clean energy, but they can also harm the environment. Species that use rivers to reproduce are often hurt by dams. In the Northwest of the US, the population of fishes has dropped from 16 million to 2.5 million since hydro-electric plants were built on the Columbia River. Dams all over the world have hurt some species. 

  The highest dam in the Unites States is located near Oroville, California. The Oroville Dam towers 230 meters and is more than a mile wide. This dam was built in 1968, 22 years after the Hoover Dam. The Hoover Dam, on the Nevada-Arizona border controls the Colorado river. It is 221 meters high and has 2.6 million hectare-meters of water.

The highest dam in the world is the Nurek Dam on the Vakhsh River in Tadzikistan, a country in central Asia. This dam is 300 meters tall. 

Which of the following statements is NOT true according to the passage?              

A. Some dams are built for controlling a river’s water flow.

B. Hydro-electric power is usually produced through a dam.

C. Dams can offer energy and they are harmless to the environment.

D. Generally speaking, where there is a dam, there is a man-made lake.

The third paragraph mainly tells us _____.                          

  A. how hydro-electric power is produced

  B. What a turbine is and how it works 

  C. how the magnets and the metal coils work

  D. how the falling water passes through a turbine                     

The dam which controls the Colorado river is ____.                  

A. the Oroville Dam  B. the Hoover Dam  C. the Nurek Dam  D. the Vakhsh Dam

A dam is a man-made structure built across a river. Most dams are built to control a river’s water flow, improve navigation and control flooding. However, some dams are built to produce hydro-electric power.

Hydro-electric power is produced as water passes through a dam, and into a river below. The more water that passes through a dam, the more energy is produced. Once a dam is built, a man-made lake is created behind the dam.

Electricity is produced by a kind of equipment called a turbine(水轮机). Turbines contain metal coils(线圈) surrounded by magnets(磁铁). When the magnets move round rapidly over the metal coils, electricity is produced. Turbines are located inside dams. The falling water makes the magnets go around the coils.

Dams provide clean energy, but they can also harm the environment. Species that use rivers to reproduce are often hurt by dams. In the Northwest of the US, the population of fishes has dropped from 16 million to 2.5 million since hydro-electric plants were built on the Columbia River. Dams all over the world have hurt some species. 

  The highest dam in the Unites States is located near Oroville, California. The Oroville Dam towers 230 meters and is more than a mile wide. This dam was built in 1968, 22 years after the Hoover Dam. The Hoover Dam, on the Nevada-Arizona border controls the Colorado river. It is 221 meters high and has 2.6 million hectare-meters of water.

The highest dam in the world is the Nurek Dam on the Vakhsh River in Tadzikistan, a country in central Asia. This dam is 300 meters tall. 

Which of the following statements is NOT true according to the passage?              

A. Some dams are built for controlling a river’s water flow.

B. Hydro-electric power is usually produced through a dam.

C. Dams can offer energy and they are harmless to the environment.

D. Generally speaking, where there is a dam, there is a man-made lake.

The third paragraph mainly tells us _____.       56-60 ADB                    

  A. how hydro-electric power is produced

  B. What a turbine is and how it works 

  C. how the magnets and the metal coils work

  D. how the falling water passes through a turbine                     

The dam which controls the Colorado river is ____.                  

A. the Oroville Dam  B. the Hoover Dam  C. the Nurek Dam  D. the Vakhsh Dam

A new study shows one of the largest glaciers① in Greenland is becoming smaller and speeding to the sea faster than scientists expected. If it continues, Greenland itself could become much smaller during this century and global seas could rise as much as 3 feet.

The rates② of change that we’re noticing are much higher than expected. If these rates continue, it is not unlikely that Greenland could shrink③ by several tens of percent this century. However, it’s not known how quickly this coastal response of the Greenland ice sheet melting will have an effect on the vast inland ice.

Greenland is the world’s largest island, covering an area more than three times the size of Texas. Some 81 percent of it is covered by ice, and there are many glaciers. Glaciers are like slow-moving rivers of ice. Where a glacier meets the sea, its weight keeps it firmly resting on the bottom. A glacier’s front is the point where the water is deep enough that the glacier floats.

Since the 1970s, the front of Helheim stayed in the same place. Then it began melting rapidly, moving back 4.5 miles from 2001 through this past summer. It has also grown thinner, from top to bottom, by more than 130 feet since 2001. And over these past four years, its trip to the sea has sped up from about 70 feet per day to nearly 110.

The melting is driven by a warmer climate. Temperatures in Greenland have risen more than five degrees Fahrenheit in the last decade. Since most of Greenland’s ice is on land, seas will rise as the ice melts. If all Greenland’s ice sheet melted, oceans would be 15-20 feet higher. Nobody expects that to happen anytime soon.

Notes:

① glacier  n.  冰川

② rate  n.  比率

③ shrink  v.  缩小

1. Which of the following about the glaciers is TRUE?

  A. Glaciers only lie in Greenland.        B. Water in glaciers is more than sea water.

  C. Glaciers sometimes float on the water.  D. Glaciers can increase the water level of lakes.

2. According to the text, we know that Greenland ______.

  A. belongs to Canada                  B. is the largest island in North America

  C. is all covered with glaciers            D. is sinking under the sea level

3. Which of the following may be the result of the disappearing of Greenland glaciers?

  A. the climate of the world will be warmer.

  B. the glaciers in other area will be bigger.

  C. It will be easy for explorers to visit the island.

  D. Some coastal cities may be under the sea.

A lesson in caring
It was a cold evening. My daughter and I were walking up Broadway. I didn’t notice a guy sitting inside a cardboard box. But Nora    36    . She wasn’t even four, but she   37    at my coat and said, “That man’s cold. Daddy, can we take him home?”
I don’t remember my   38    . But I do remember a sudden   39    feeling inside me. I had always been delighted at how much my daughter noticed in her   40     , whether it was     41    flying or children playing. But now she was noticing   42    and beggary.
A few days later, I saw an article in the newspaper about volunteers who picked up a food package from a nearby school on a Sunday morning and   43     it to an elderly person. It was quick and easy. I signed us up. Nora was   44    about it. She could understand the importance of food, so she could easily see how   45    our job was. When Sunday came, she was ready, but I had to    46    myself to leave the house to fetch the food package. On my way to the school, I fought an urge (强烈愿望) to turn    47    . The Sunday paper and coffee were waiting for me at home. Why do this?   48    , we phoned the elderly person we’d been appointed. She   49    us right over.
The building was in a bad state. Facing us was a silver-haired woman in an old dress. She took the package and asked us to come in. Nora ran inside. I unwillingly followed.   50     inside, I saw that the department belonged to someone poor. Our hostess showed us some photos. Nora played and when it came time to say goodbye, we three hugged. I walked home    51    .
Professionals call such a(n)   52    “a volunteer opportunity”. They are opportunities and I’ve come to see. Where else but as volunteers do you have the opportunity to do something    53     that’s good for others as well as for yourself? Nora and I regularly serve meals to needy people and   54     clothes for the homeless. Yet, as I’ve    55     her grow over these past four years, I still wonder—which of us has benefited more?