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The conference was hailed as a great success. published challenged acclaimed guided
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The defendant asked for a number of other offences to be taken into account. calculation computation consideration assessment
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I did remember, but only dimly. inadequately hardly faintly sufficiently
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Even in a highly modernized country, manual work is still needed. expressive physical exaggerated dubious
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His breathing was steady. regular usual common ordinary
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I doubt they’ll be able to help but it’ s worth trying. growing wrapping hiding attempting
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When she was invited to the party, she readily accepted. willingly suddenly firmly quickly
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The deadly disease has affected these animals. contagious serious fatal worrying
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Lead is potentially damaging to children’ s health. slight surprising sudden harmful
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We aim to increase the speed of delivery. velocity impulse ratio atrocity
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Exposure to the Sun can accelerate the ageing process. step up decrease stop control
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More resources are being allocated to the project. persuaded assigned asked ordered
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The system is designed to be used in conjunction with a word processing program. together in succession in alliance in connection
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These old buildings are gorgeous. ridiculous lovely magnificent peculiar
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They scattered after dinner. separated fled departed spread
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Plants in Desert
Only special plants can survive the terrible climate of a desert, for these are regions where the annual range of the soil temperature can be over 75 °C . Furthermore, during the summer there are few clouds in the sky to protect plants from the sun’ s ray. Another problem is the fact that there are frequently strong winds that drive small, sharp particles of sand into the plants, tearing and damaging them. The most difficult problem for all forms of plant life, however, is the fact that the entire annual rainfall occurs during a few days or weeks in spring.
Grasses and flowers in desert survive from one year to the next by existing through the long, hot, dry season in the form of seeds. These seeds remain inactive unless the right amount of rain falls. If no rain falls, or if insufficient rain falls, they wait until the next year, or even still the next. Another factor that helps these plants to survive is the fact that their life cycles are short. By the time the water from the spring rains disappears—just a few weeks after it falls—such plants no longer need any.
The perennials(多年生植物)have special features that enable them to survive as plants for several years. Thus, nearly all desert perennials have extensive root systems below ground and a small shoot system above ground. The large root network enables the plant to absorb as much water as possible in short time. The small shoot system, on the other hand, considerably limits water loss by evaporation(蒸发).
Another feature of many perennials is that after the rainy season they lose their leaves in preparation for the long, dry season, just as trees in wetter climates lose theirs in preparation for the winter. This reduces their water loss by evaporation during the dry season. Then, in next rainy season, they come fully alive once more, and grow new branches, leaves and flowers, just as the grasses and flowers in desert do.
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Science Fiction
1 Amongst the most popular books being written today are those which are usually classified as science fiction. Hundreds of titles are published every year and are read by all kinds of people. Furthermore, some of the most successful films of recent years have been based on science fiction stories.
2 It is often thought that science fiction is a fairly new development in literature, but its ancestors can be found in books written hundreds of years ago. These books were often concerned with the presentation of some form of ideal society, a theme which is still often found in modern stories.
3 Most of the classics of science fiction, however, have been written within the last hundred years. Books by writers such as Jules Verne and H. G. Wells, to mention just two well-known authors, have been translated into many languages.
4 Modern science fiction writers don’t write about men from Mars(火星)or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future worlds which are a reflection of the world which we live in now. Because of this, their writing has obvious political undertones(含义).
5 In an age where science fact frequently overtakes(超过)science fiction, the writers may find it difficult to keep ahead of scientific advances. Those who are sufficiently clear-sighted to see the way we are going, however, may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.
A. Popularity of Science Fiction
B. A Fairly New Development
C. Classics of Science Fiction
D. Difficulty in Keeping Ahead of Scientific Adventure
E. Its Origin
F. Themes of Modern Science Fiction
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A. concerned with the problems to solve in the future
B. to keep ahead of scientific advances
C. have political implication
D. a current theme
E. read worldwide
F. a recurrent theme
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Adaptation of Living Things
Certain animals and plants develop characteristics that help them cope with their environment better than others of their kind. This natural biological process is called adaptation. Among the superior characteristics developed through adaptation are those that may help in getting food or shelter, in providing protection, and in producing and protecting the young. That results in the evolution of more and more organisms(微生物)that are better fitted to their environments.
Each living thing is adapted to its way of life in a general way, but each is adapted especially to its own distinct class. A plant, for example, depends upon its roots to fix itself firmly and to absorb water and inorganic(无机的)chemicals. It depends upon its green leaves for using the sun’ s energy to make food from inorganic chemicals. These are general adaptations, common to most plants. In addition, there are special adaptations that only certain kinds of plants have.
Many animals have adaptations that help them escape from their enemies. Some insects are hidden by their body color or shape, and many look like a leaf or a little branch. The coats of deer are colored to mix with the surroundings. Many animals have the ability to remain completely still when an enemy is near.
Organisms have a great variety of ways of adapting. They may adapt in their structure, function, and genetics; in their development and production of the young; and in other respects. An organism may create its own environment, as do warm-blooded mammals(哺乳动物), which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather. Usually adaptations are an advantage, but sometimes an organism is so well adapted to a particular environment that, if conditions change, it finds it difficult or impossible to readapt to the new conditions.
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Older Volcanic Eruptions
Volcanoes were more destructive in ancient history, not because they were bigger, but because the carbon dioxide they released wiped out life with greater ease.
Paul Wignall from the University of Leeds was investigating the link between volcanic eruptions and mass extinctions. Not all volcanic eruptions killed off large numbers of animals, but all the mass extinctions over the past 300 million years coincided with huge formations of volcanic rock. To his surprise, the older the massive volcanic eruptions were, the more damage they seemed to do. He calculated the “killing efficiency“ for these volcanoes by comparing the proportion of life they killed off with the volume of lava(熔岩)that they produced. He found that size for size, older eruptions were at least 10 times as effective at wiping out life as their more recent rivals.
The Permian(二叠纪)extinction, for example, which happened 250 million years ago, is marked by floods of volcanic rock in Siberia that cover an area roughly the size of western Europe. Those volcanoes are thought to have pumped out about 10 gigatonnes(十亿吨)of carbon as carbon dioxide. The global warming that followed wiped out 80 percent of all marine genera(种类)at the time, and it took 5 million years for the planet to recover. Yet 60 million years ago, there was another huge amount of volcanic activity and global warming but no mass extinction. Some animals did disappear but things returned to normal within ten thousands of years. “The most recent ones hardly have an effect at all, “ Wignall says. He ignored the extinction which wiped out the dinosaurs 65 million years ago, because many scientists believe it was primarily caused by the impact of an asteroid(小行星). He thinks that older volcanoes had more killing power because more recent life forms were better adapted to dealing with increased levels of CO2. Vincent Courtillot, director of the Paris Geophysical Institute in France, says that Wignall’ s idea is provocative. But he says it is incredibly hard to do these sorts of calculations. He points out that the killing power of volcanic eruptions depends on how long they lasted. And it is impossible to tell whether the huge blasts lasted for thousands or millions of years. He also adds that it is difficult to estimate how much lava prehistoric volcanoes produced, and that lava volume may not necessarily correspond to carbon dioxide emissions.
