91. Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests...

81. Television the most pervasive and persuasive of modern technologies, marked by rapid change and growth, is 0 81. television the most pervasive and persuasive of modern technologies, marked by rapid change and growth, is moving into a ne...

71. People in prehistoric times created paints by grinding materials such as plants and clay into power and then adding water. 71.史前的人们制造颜料是将植物和泥土等原料磨成粉末，然后加水。 72. Often very annoyin...

61. buyers and sellers should be aware of new developments in technology can and does affect marketing activities. 61.购买者和销售者都应该留意技术的新发展，原因很简单，因为技术能够并且已经影响着营销活动...

51. using many symbols makes it possible to put a large amount of information on a single map. 51.使用多种多样的符号可以在一张地图里放进大量的信息。 52. anarchism is a term describing a cluster of doctrines and atti...