10. Which of the following would be the most suitable title for the passage?

  A. Anxious rats and relaxed rats

  B. Anxiety - a serious mental disease

  C. Scientific research into the brain is important

  D. Brain chemical may play key role in anxiety

 (3)

     The Earth’s axis(轴) is an imaginary line that runs through the middle of the Earth from the North Pole to the South Pole. The axis of the earth is tilted (倾斜) about 23.5 degrees. This tilt of the earth results in our seasons.

     In June, the Northern Hemisphere (半球) is tilted toward the sun, so the people in the Northern Hemisphere have longer and warmer days. The days are shorter and colder in the Southern Hemisphere in June, because the Earth is tilted away from the sun. The days start getting shorter in the Northern Hemisphere and longer in the Southern Hemisphere after about June 21. This is the first day of summer in the Northern Hemisphere and the first day of winter in the southern hemisphere. Daytime lasts exactly as long as nighttime on the first day of autumn (about September 21) and the first day of spring (about March 21). The first day of winter in the Northern Hemisphere, usually December 21, is the shortest day of the year in the Northern Hemisphere and the longest day of the year in the Southern Hemisphere.

     The days are longer in summer and shorter in winter the further you move from the equator. It’s generally dark on a summer night in Florida by 8:30 p.m., but in Vermont, there will still be some light at 10:00 p.m. The situation is reversed(相反的) in winter, where the sun will go down in Vermont by 3:45 p.m. while there remains light in Florida until 5:15 p.m.

     Northern Alaska is called the “Land of the Midnight Sun” because it never gets dark during the summer months. That part of the Earth is facing the sun all day and all night. Antarctica never sees daylight during those months. The situation is reversed in December and January when northern Alaska never sees the sun while it continues to light the sky at night in Antarctica.

5. In the next part of the passage, the author might continue to talk about       .

  A. how to determine what intelligence is

  B. how education should be changed

  C. how to judge whether a person is intelligent

  D. how an unintelligent person should be taught

 (2)

A chemical important of brain development may play a role in explaining why some people are genetically (由基因决定地) likely to suffer from anxiety and could lead to new treatments, U.S. researchers said.

They said highly anxious rats which were kept had very low levels of a brain chemical called fibroblast growth factor 2 or FGF2, compared with rats that were more relaxed. But when they improved the anxious rats’ living conditions - giving them new toys to explore and a bigger cage to live in - levels of this brain chemical increased and they became less anxious.

“The levels of this brain chemical increased in response to the experiences that the rats were exposed to. It also decreased their anxiety”. Javier Perez of the University of Michigan said in a telephone interview. “It made them behave the same way as the rats that were relaxed”, he said.

In a former study of people who were severely depressed before they died, the team found the gene that makes FGF2 was producing very low levels of the growth factor, which is known primarily for organizing the brain during development and repairing it after injury.

Perez thinks the brain chemical may be a marker for genetic vulnerability (脆弱性) to anxiety and depression. But it can also respond to changes in the environment in a positive way, possibly by preserving new brain cells.

While both the calm and anxious rats produced the same number of new brain cells, these cells were less likely to survive in the high-anxiety rats, the team found. Giving the rats better living conditions or injecting them with FGF2 helped improve cell survival.

“This discovery may pave the way for new, more specific treatments for anxiety that will not be based on sedation(药物镇静), but will instead fight the real cause of the disease,” Dr. Pier Vincenzo Piazza from France said in a statement.

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