题目内容

基托折断的修理在基托组织面灌注石膏时起分离作用的除了

A. 蒸馏水
B. 石蜡油
C. 凡士林
D. 分离剂
E. 肥皂水

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下列哪项不是人工牙折断、脱落的原因

A. 咬合撞击力过大
B. 填塞时残留玻璃纸
C. 人工牙盖嵴面蜡质未去净
D. 人工牙盖嵴面涂有分离剂
E. 磨改了人工牙的盖嵴部

红霉素与口服避孕药联用时降低避孕效果其原因是

A. 抑制肝药酶使其不能正常代谢
B. 影响口服避孕药的吸收
C. 改变肠道菌群
D. 促进口服避孕药的代谢
E. 影响口服避孕药的血药浓度

In recent years, railroads have been combining with each other, merging into super systems, causing heightened concerns about monopoly. As recently as 1995, the top four railroads accounted for under 70 percent of the total ton-miles moved by rails. Next year, after a series of mergers are 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 argued 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 travelling 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 only one rail company serves most shippers. Railroads typically charge such "captive" shippers 20 to 30 percent more than they do when another railroad is competing for the business. 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.Railroads justify rate discrimination against captive shippers on the grounds that 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.Many captive shippers also worry they will soon be this with a round of huge rate increases. The railroad industry as a whole, despite its brightening fortuning fortunes, still does not earn enough to cover the cost of the capital it must invest to keep up with its surging traffic. Yet railroads continue to borrow billions to acquire one another, with Wall Street cheering them on. Consider the $ 10.2 billion bid by Norfolk Southern and CSX to acquire Conrail this year. Conrail’s net railway operating income in 1996 was just $ 427 million, less than half of the carrying costs of the transaction. Who’s going to pay for the rest of the bill Many captive shippers fear that will, as Norfolk Southern and CSX increase their grip on the market. It can be inferred from paragraph 3 that ().

A. shippers will be charged test without a rival railroad
B. there will soon be only one Railroad Company nationwide
C. overcharged shippers are unlikely to appeal for rate relief
D. a government board ensures fair play in railway business

塑料热处理过程中加热过快可导致

A. 塑料内出现散在性小气泡
B. 塑料表面不平整
C. 塑料表面出现龟裂
D. 塑料内出现圆形大气泡
E. 塑料颜色变浅

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