If the population of the earth goes on increasing at its current rate, there will eventually not be enough resources left to sustain life in the planet. By the middle of the 21 st century, if present trends go on, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on the earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Cart Sagan.
Sagan believes that before the earth’s resources are completely exhausted it will be possible to change that atmosphere of Venus and so create a new world almost as large as the earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
S
A. Lack of oil.
B. Lack of food.
C. Lack of space.
D. Lack of resources.
If the population of the earth goes on increasing at its current rate, there will eventually not be enough resources left to sustain life in the planet. By the middle of the 21 st century, if present trends go on, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on the earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Cart Sagan.
Sagan believes that before the earth’s resources are completely exhausted it will be possible to change that atmosphere of Venus and so create a new world almost as large as the earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
S
A. As long as algae produces enough oxygen on Venus, people can land there.
B. To live on Venus is the only way to ensure the survival of human race.
C. Venus is possibly very similar to the earth both in size and mass.
D. Life on Venus will be pleasant at first.
If the population of the earth goes on increasing at its current rate, there will eventually not be enough resources left to sustain life in the planet. By the middle of the 21 st century, if present trends go on, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on the earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Cart Sagan.
Sagan believes that before the earth’s resources are completely exhausted it will be possible to change that atmosphere of Venus and so create a new world almost as large as the earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sag
A. we fire the rockets containing algae into the atmosphere of Venus
B. we change Venus temperature
C. we make it possible to rain on Venus
D. we change the atmosphere on Venus
Teenagers and young adults in the US are increasingly being diagnosed with skin cancer, according to doctors who warn that the development could lead to an outbreak of deadly aches on the skin as these patients get older. Doctors are especially disturbed by the numbers of younger people they are treating, which suggests that messages about avoiding the sun still aren’t getting through and that the tanned skin (晒黑的皮肤) that was made popular by French designer Coco Chanel in the 1920s remains a sought- after look today.
Although doctors lack the data to know what exactly is behind the rise in skin cancers among young people, they suggest several factors: more time in the sun, improper use of sunscreens and a rise in tanning salon (阳光浴沙龙) visits. Skin doctors believe that young people are generally spending more time in the sun than their parents did and are either not using enough sunscreen or failing to apply it properly. They also claimed that many Americans,
A. from 1986 to 1996
B. from 1987 to 1997
C. during 1997
D. during 1996
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