文档介绍：老 PREP2 正确句子 151 1. Since the start of the space age, orbits near Earth have e more and more littered, often from the intentional discarding of lens caps, packing material, fuel tanks, and payload covers. 2. With the Louisiana Purchase in 1803, the United States acquired 828,000 square miles for about four cents an acre, more than doubling its size and bringing its western border within reach of the Pacific Ocean. 3. Defying efforts by policymakers on both sides of the Atlantic to restrain it, the United States dollar continued its rise, reaching its highest level in six years against the German mark. 4. The Sun is the source not only of heat and light, but also ofa continuous stream of atomic particles known as the solar wind. 5. Like their male counterparts, women scientists are above average in terms of intelligence and creativity, but unlike men of science, women of science have had to work against the grain of occupational stereotyping to enter a "man's world." 6. What scientists know about dinosaur es from studies of the cranium, the bony house of the brain located in the back of the skull. 7. So-called green taxes, which exact a price for the use of polluting or nonrenewable fuels, are having a positive effect on the environment and natural resource base of countries as varied as China, herlands, and Hungary. 8. Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it had long appeared immune to human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer. 9. The Environmental Protection Agency frequently puts mandatory controls on toxic substances that present as little risk as one chance ina million of causing cancer. 10. The rise of the Incan empire rested not only on the Incas' military might and the ability of their rulers but also on their imposition ofa anized economic and political system on many different ethnic