北京市西城区2006年抽样测试英语试卷

64．What is the main idea of this passage?
 A．How exercise makes people strong. B．How to get good scores on a test.
 C．How exercise helps the brain. D．How the brain can change.
65．According to the passage ,what is the connection between exercise and brain development?
 A．Exercise helps make our blood vessels.
 B．Physical exercise helps us think better.
 C．The brain needs special mental exercise.
 D．The more exercise ,the bigger the brain.
66．The smallest amount of exercise required to gain any benefit is         .
 A．three hours per week B．40 hours per week
 C．three hours per day D．40 hours per month
67．Why is yoga suggested for seniors?
 A．It does good to the joints of old people.
 B．It does not increase the heart rate.
 C．It includes learning new actions.
 D．It can be done in groups.

D
 Recognized as the largest desert in the world, the Sahara Desert runs across North Africa, covering over 3 million square miles from the Atlantic Coast to the Nile River Valley .Except for an occasional oasis（绿洲）,this vast land is mainly made up of sand ,stones ,and worn out mountains .The burning sun causes daytime temperatures to rise to nearly 70 degrees in the shade ,and days without rain commonly last for years.
 Paintings found on the walls of caves in the Sahara Desert suggest that a few thousand years ago ,large quantities of plants grew there and covered the desert floor. Many curious and unusual insects ,birds and animals got enough food that allowed them to grow and reproduce .At that time ,huge river systems and many oases supported growing communities（社团，社区）where a large number of people lived .
 Research scientists believe that the land became a desert for several reasons .For centuries people there have wandered from place to place in search of food ,water ,and grazing（吃草）land for their animals .These people have always considered the number of animals they have as a sign of wealth .It is considered more important to have 100 sick and starving animals than 15 healthy ones .The large herds （群）have been allowed to go freely and graze on desert plants and grass. Over time ,large sections of land have been left uncovered .In addition to allowing overgrazing, these people cut down whatever trees they could find and used them for firewood. The sand was unable to hold on to the great heat of the day ,so nighttime temperatures often drop below freezing and nothing was left to hold the soil together.
 Scientists have been studying different ways to bring back the green desert .Through research and experiments ,they hope to be able to produce plants that will once again support the life there .Huge holes filled with much water lie under the desert surface .Scientists believe this rainwater simply flew down through the sand over hundreds of years and collected in the big ,rocky holding tanks .By making use of the sun’s power ,scientists in the Sahara have made experiments in which they got huge amount of electricity .This electricity was then used to operate drilling machines and pumps to pull the rainwater from the underground tanks. By drilling the hole one mile deep into the floor of the desert ,one machine was able to recover more than 80 gallons of ice-cold water each second ,or 288,000 gallons per hour.
Scientists have had some success turning this wasteland into useful farmland. Today the desert is dotted with huge wheat fields watered by a system of pipes that carry water from the underground tanks. Farmers have also learnt that  plants grow better if seeds are planted next to stones. Studies show that stones provide protection from the sun, allowing seeds to grow in a shady and cool environment. In addition to that, greenhouses have been built to protect plants from the sunshine so that less water is needed. Another idea is to grow plants that can live on a diet of salt water, since the ocean is so near to the desert.
68．What will probably happen if the local people continue their customs and traditions ?
  A．The desert will continue to be enlarged.
  B．Tourists will begin traveling to North Africa.
  C．More oases will begin to appear across the desert.
 D．The number of healthy animals will become larger.
69．Which of the following statements is a fact presented in the passage ?
  A．The desert is rich in beautiful color and scenery.
  B．Camels can go for days without drinking any water.
  C．The Sahara will one day become a beautiful garden.
  D．Large river systems once supported many communities.
70．The author of the passage provides evidences（证据）that scientists are           .