A.accounted for B.for C.grounds A. Railroads justify rate discrimination against captive shippers on the【T1】______ that B. another railroad is competing【T2】______ the business C. the top four railroads【T3】______under 70 percent In recent years, railroads have been combining with each other, merging into super systems, causing heightened concerns about monopoly. As recently as 1995,【T4】______ of the total ton-miles moved by rails. Next year, after a series of mergers is completed, just four railroads will control well over 90 percent of all the freight moved by major rail carriers. Supporters of the new super systems argue that these mergers will allow for substantial cost reductions and better coordinated service. Any threat of monopoly, they argue, is removed by fierce competition from trucks. But many shippers complain that for heavy bulk commodities traveling long distances, such as coal, chemicals, and grain, trucking is too costly and the railroads therefore have them by the throat. The vast consolidation within the rail industry means that most shippers are served by only one rail company. Railroads typically charge such "captive" shippers 20 to 30 percent more than they do when【T5】______. Shippers who feel they are being overcharged have the right to appeal to the federal government's Surface Transportation Board for rate relief, but the process is expensive, time consuming, and will work only in truly extreme cases. 【T6】______ in the long run it reduces everyone's cost. If railroads charged all customers the same average rate, they argue, shippers who have the option of switching to trucks or other forms of transportation would do so, leaving remaining customers to shoulder the cost of keeping up the line. It's theory to which many economists subscribe, but in practice it often leaves railroads in the position of determining which companies will flourish and which will fail. "Do we really want railroads to be the arbiters of who wins and who loses in the marketplace?" asks Martin Bercovici, a Washington lawyer who frequently represents shipper.

【正确答案】 C

【答案解析】解析：空格前一句的意思为：近年来，各个铁路公司都一直在进行合并而成为超级系统，这引起了人们对垄断的日益关注。空格后一句的意思为：明年，经过一系列的合并之后，这四条铁路将控制主要货运公司全部运输货物的90％以上。故空格所在句的意思应为：在1995年四条最大的铁路运输量不到总吨英里数的70％。所以，C项符合题意。

【正确答案】 B

【答案解析】解析：空格前一句的意思为：铁路业的大规模合并意味着托运人服务的铁路公司仅此一家。空格后一句的意思为：那些觉得运费过高的人有权向联邦政府地面运输委员会投诉，要求给予运费补贴。然而，这个过程既耗时，又费钱，而且只有在极端的情况下才能如此。故空格所在句的意思为：这样，一般铁路会比有竞争对手时向“受制”的托运人多收20％～30％的费用。所以，B项符合题意。