| The discovery of the Antarctic not only
proved one of the most interesting of all geographical adventures, but created
what might be called "the heroic age of Antarctic exploration". By their
tremendous heroism, men such as Shackleton, Scott, and Amundsen caused a new
continent to emerge from the shadows, and yet that heroic age, little more than
a century old, is already passing. Modern science and inventions are
revolutionizing the techniques of former explorers, and, although still calling
for courage and feats of endurance, future journeys into these icy wastes will
probably depend on motor vehicles equipped with caterpillar traction rather than
on the dogs that earlier discoverers found so invaluable. Few realize that this Antarctic continent is almost equal in size to South America, and enormous field of work awaits geog A. About 100 years ago. B. In this century. C. At the beginning of the 19th century. D. In 1798. [单项选择]What important discovery about seismic waves does the instructor mention
A. They occur at regular intervals. B. They can withstand great heat. C. They travel through the Earth’s interior. D. They can record the Earth’s internal temperature. [单项选择]
FREEZING FOOD 1 The discovery of freezing has changed our eating habits more than any other related invention. Because many foods contain large amounts of water, they freeze solidly at or just below 32 degrees Fahrenheit. When we lower the temperature to well below the freezing point and prevent air from penetrating the food, we retard the natural process of decay that causes food to spoil. Freezing preserves the flavor and nutrients of food better than any other preservation method. When properly prepared and packed, foods and vegetables can be stored in the freezer for one year. 2 Most vegetables and some fruits need blanching before they are frozen, and to avoid this step would be an expensive mistake. The result would be a product largely devoid of vitamins and minerals. Proper blanching curtails the enzyme action, which vegetables require during their growth and ripening but which continues after maturation and w A. To state that blanching is expensive but very effective B. To warn that not blanching will harm the food’s nutritional value C. To emphasize the importance of blanching only a few items at a time D. To show that many people waste food by blanching improperly [单项选择]An accidental discovery has brought seismologists(地震学家) one step closer to being able to predict earthquakes. As part of an unrelated effort to measure underground changes caused by shifts in barometric pressure (大气压力), a team of researchers found that increases in subterranean pressure(地下压力) preceded earthquakes along California’s San Andreas Fault(断层) by as much as 10 hours. If follow-up tests advance the findings, seismologists may eventually be able to provide a few hours’ notice for people to find safe places prior to quakes.
Researchers used a high-tech equivalent of a stereo speaker lowered into a bore hole near Parkfield, Calif., a half-mile deep and five yards from a measuring device. For two months beginning in late 2005, researchers transmitted pulse signals three times per second, from the speaker to the measuring device, calculating travel time between the two stations. Surprised scientists learned the seismic waves slowed dramatically on only two occasions: two hours 我来回答: 提交
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