1.Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance, acting as sentinels and sounding a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.
2.Lacking information about energy use, people tend to overestimate the amount of energy used by visible equipment, such as lights, that must be turned on and off and underestimate that used by unobtrusive equipment, such as water heaters.
3.Teratomas are unusual forms of cancer in that they are composed of tissues such as tooth and bone, tissues not normally found in the organ in which the tumor（瘤） appears.
4.It seems likely that a number of astronomical phenomena, such as the formation of planetary nebulas, are caused by the interaction of two stars orbiting each other at close range.
5.By offering lower prices and a menu of personal communications options, such as caller identification and voice mail, the new telecommunications company has not only captured customers from other phone companies but also forced these companies to offer competitive prices.
6.Aware of the connotations of the numbers 1 and 2 and the letters A and B, companies conducting consumer taste tests of foods or beverages typically choose numbers such as 697 or 483 to label the products.
7.In the major cities of industrialized countries at the end of the nineteenth century, important public places such as theaters, restaurants, shops, and banks had installed electric lighting, but electricity was in less than one percent of homes, where lighting was still provided mainly by candles or gas.
8.Whereas the use of synthetic fertilizers has greatly expanded agricultural productivity in many parts of the world, an increase in their use can create serious environmental problems such as water pollution, and their substitution for more traditional fertilizers may accelerate soil structure deterioration and soil erosion.
9.The survival of coral colonies, which are composed of innumerable tiny polyps living in a symbiotic relationship with brilliantly colored algae, is being threatened, experts say, not only by pollutants such as agricultural runoff, oil slicks, and trash, but also by dropped anchors, probing divers, and global warming. | 
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发表于 2006-10-31 13:55:00
