单选题 There are four passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C andD. You should decide on the best choice and mark the corresponding letter on the Answer Sheet. Overland transport in the United States was still extremely primitive in 1790. Roads were few and short, usually extending from inland communities to the nearest river town or seaport. Nearly all interstate commerce was carried out by sailing ships that served the bays and harbors of the seaboard. Yet, in 1790 the nation was on the threshold of a new era of road development. Unable to finance road construction, states turned for help to private companies, organized by merchants and land speculators who had a personal interest in improved communications with the interior. The pioneer in this move was the state of Pennsylvania, which chartered a company in 1792 to construct a turnpike, a road for the use of which a toll, or payment, is collected, from Philadelphia to Lancaster. The legislature gave the company the authority to erect tollgates at points along the road where payment would be collected, though it carefully regulated the rates.(The states had unquestioned authority to regulate private business in this period.) The company built a gravel road within two years, and the success of the Lancaster Pike encouraged imitation. Northern states generally relied on private companies to build their toll roads, but Virginia constructed a network at public expense. Such was the road building fever that by 1810 New York alone had some 1, 500 miles of turnpikes extending from the Atlantic to Lake Erie. Transportation on these early turnpikes consisted of freight carrier, wagons and passenger stagecoaches. The most common road freight carrier was the Conestoga wagon, a vehicle developed in the mid-eighteenth century by German immigrants in the area around Lancaster, Pennsylvania. It featured large, broad wheels able to negotiate all, but the deepest ruts and holes, and its round bottom prevented the freight from shifting on a hill. Covered with canvas and drawn by four to six horses, the Conestoga wagon rivaled the log cabin as the primary symbol of the frontier. Passengers traveled in a variety of stagecoaches, the most common of which had four benches, each holding three persons. It was only a platform on wheels, with no springs; slender poles held up the top, and leather curtains kept out dust and rain.