高中英语unit5meetingyourancestors测试练习新人教版选修8

高中英语unit5meetingyourancestors测试练习新人教版选修8内容摘要：

und, such as the way in which something such as a town, garden, or building is arranged and traces of old walls and roads. The technique involves taking photographs with conventional cameras and filming from airplanes, helicopters, hotair balloons, or other airborne vehicles. Geographic Information System (GIS) contains a large amount of field data archeologists typically collect in and around excavation sites. While in the field, archeologists use GIS on their puters to make and manage detailed site maps, and they can bine the results of remotesensing tests with maps of the region c reated with the aid of Global Positioning System. Resulting maps sort the most archeologically promising areas and display these sites threedimensionally. Ranging in size from small handheld models that one places against the ground to larger ones that one drags across a site, Ground Perating Radar (GPR) devices use lowpower radio waves to detect changes underground. Unlike traditional radar, which broadcasts into the air and uses a dish to focus the returned waves, GPR uses a small but sensitive receiver placed directly against the ground. Depending on their needs, archeologists can adjust radio frequencies upward for shallow sites or downward for deeper areas, though GPR devices produce the greatest definition (清晰度 ) when reading depths of three feet or less. 39. We can learn from the text that the remotesensing tools . A. will replace traditional archeological tools B. are more difficult to use than traditional tools C. have been widely and efficiently used in archeology D. help archaeologists discover more archaeological sites 40. Aerial photography is helpful . A. in seeing what can’ t be seen on the ground B. in analyzing how old an archaeological site is C. in reflecting the changes of an archaeological site D. in taking largesized photos of an archaeological site 41. Ground Perating Radar (GPR) devices are different from traditional radar in that . A. their sizes are pletely different B. traditional radar uses lowpower radio waves C. the length of waves they send out is different D. GPR devices can detect changes underground 42. Archeologists can get a detailed site map by . A. aerial photography B. Geographic Information System C. Global Positioning System D. Ground Perating Radar C It may sound strange, but cutting down a real tree for Christmas is actually greener than going with the artificial kind, one scientist says. “ It is a little confusing to people,” said Clint Springer, a biologist at Saint Joseph’ s University in Philadelphia. Because of concerns over deforestation (砍伐森林 ) around the world, many people naturally worry that buying a real tree might contribute to that problem. But most Christmas trees for sale these days are grown not in the forest but on tree farms for the purpose of being cut. Moreover, from the viewpoint of greenhouse gases, real trees are “ the obvious choice” . Live trees actively release oxygen as they grow, and meanwhile remove carbon dioxide from the atmosphere. After they have been cut and Christmas is over, they’ re usually cut into smaller pieces for mulch (覆盖物 ). As mulch, the bits of trees very slowly release carbon dioxide back into the atmosphere. So in the end, a real Christ mas tree is carbon neutral, putting the same amount of carbon dioxide back into the air as it took out (although much more slowly). The tree farms that grow the trees also replant after the trees are cut. Artificial trees, on the other hand, don’ t e out even in the carbon balance. Petroleum (石油 ) is used to make the plastics in artificial trees and lots of carbon dioxidecreating energy is required to make and transport them. Because these trees just end up in the places where waste is buried under the ground after use, “ those greenhouse gases are lost forever,” Springer said. 43. The author presents the text mainly by . A. giving descriptions B. making parisons C. listing figures D. analyzing differe。