[单项选择]第一篇 　　 Water 　　The second most important constituent (构成成份) of the biosphere (生物圈) is liquid water. This can only exist in a very narrow range of temperatures, since water freezes at 0℃ and boils at 100℃. Life as we know it would only be possible on the surface of a planet which had temperatures somewhere within this narrow range. 　　The earth’s supply of water probably remains fairly constant in quantity. The total quantity of water is not known very accurately, but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers. Most of it is in the form of the salt water of the oceans about 97 percent. The rest is fresh, but three quarters of this is in the form of ice at the Poles and on mountains, and cannot be used by living systems until melted. Of the remaining fractional which is somewhat less than one per cent of the whole, there is 10—20 times as much stored underground wat
A. in the center of the earth.
B. on the surface of our planet.
C. in a very narrow range of temperatures.
D. in the coastal areas of the earth.

[单项选择]第一篇 　　 Water 　　The second most important constituent (构成成份) of the biosphere (生物圈) is liquid water. This can only exist in a very narrow range of temperatures, since water freezes at 0℃ and boils at 100℃. Life as we know it would only be possible on the surface of a planet which had temperatures somewhere within this narrow range. 　　The earth’s supply of water probably remains fairly constant in quantity. The total quantity of water is not known very accurately, but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers. Most of it is in the form of the salt water of the oceans about 97 percent. The rest is fresh, but three quarters of this is in the form of ice at the Poles and on mountains, and cannot be used by living systems until melted. Of the remaining fractional which is somewhat less than one per cent of the whole, there is 10—20 times as much stored underground wat
A. remains almost unchanged.
B. has greatly increased in recent years.
C. is decreasing constantly.
D. is affected by global warming.

[单项选择]第一篇 　　 Youth Emancipation in Spain 　　The Spanish Government is so worried about the number of young adults still living with their parents that it has decided to help them leave the nest. 　　Around 55 percent of people aged 18-34 in Spain still sleep in their parents’ homes, says the latest report from the country’s state-run Institute of Youth. 　　To coax (劝诱) young people from their homes, the Institute started a "Youth Emancipation (解放)" program this month. The program offers guidance in finding rooms and jobs. 　　Economists blame young people’s family dependence on the precarious (不稳定的) labor market and increasing housing prices. Housing prices have risen 17 percent a year since 2000. 　　Cultural reasons also contribute to the problem, say sociologists (社会学家). Family ties in south Europe - Italy, Portugal and Greece - are stronger than those in middle and north Europe, said Spanish sociologist Almudena Moreno Minguez in her report "The Late
A. fight for freedom.
B. live in an independent way.
C. fight against social injustice.
D. get rid of family responsibilities.

[单项选择]第一篇 The Northern Lights The sun is stormy and has it own kind of weather. It is so hot and active that even the Sun’s gravity cannot hold its atmosphere in check! Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma, and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun, the stronger the solar wind. The solar wind constantly streams toward the Earth, but don’t worry because a protective magnetic fields surrounds our planet. The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles. The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth’s magnetic field first gets squeezed and then the magnetic field lines break and reco
A. disappearance of the Sun’s gravity.
B. unpredictable weather of the Sun.
C. fast flow of energy away from the Sun.
D. a stream of particles being blown away.