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公文写作必须及时迅速，把握时机，适应机关行政管理需要，提高机关工作效率。（）
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A．unnoticedB．unmentionedC．untouchedD．undone
A．crucialB．compulsoryC．necessaryD．urgent
Over an extended period of time it is possible for potential firms to enter or for existing firms to leave a competitive industry. In the competitive world, shifts in the productive【1】of the economy from any one line of production to others would【2】in this way. The length of the time period【3】for entry and/or exit will vary, depending upon the【4】involved. Some, like hot dog stands, may be easily and quickly【5】. Others, like textile mills, will require a longer planning and construction period. Whatever the time【6】necessary for firms to enter or exit a given industry, we【7】that period as the long run for that industry. For different industries, the long run will encompass different time spans.
The force that【8】the entry of new firms into an industry is profit【9】. When the firms in an industry are making profits, they provide the investors in those firms with higher-than-average returns on their investments. Higher-than-average returns seldom go【10】. In the long run they attract new investment and new firms. On the other hand, losses provide the【11】for firms in an industry to leave it. Losses mean that returns to investors in the industry are below the average received by investors economy-wide; however, they do not necessarily【12】that the net income of the firm is【13】. It may or it may not be. But investors will want to withdraw their investments from the loss-incurring industry and【14】in other industries where the returns will be greater.
Where profits exist, returns on investment are above average. Where losses occur, returns are below average. So investment is【15】being redirected from less valuable to more valuable uses.
(1)
Video recorders and photocopiers, even ticket machines on the railway, often seem unnecessarily difficult to use. Last December I bought myself a video cassette recorder (VCR) described as "simple to use". In the first three weeks I failed repeatedly to program the machine to record from the TV, and after months of practice I still made mistakes. I am not a lone. According to a survey last year by Ferguson, the British manufacturer, more than in four VCR owners never use the timer on their machines to record a programme: they don’t use it because they' ve found it far too hard to operate.
So why do manufacturers keep on designing and producing VCRs that are awkward to use if the problems are so obvious？ First, the problems are not obvious to technically minded designers with years of experience and trained to understand how appliances work. Secondly, designers tend to add one or two features at a time to each model, whereas you or I face all a machine’s features at once. Thirdly, although finding problems in a finished product is easy, it is too late by then to do anything about the design. Finally, if manufacturers can get away with selling products that are difficult to use, it is not worth the effort of any one of them to make improvements.
Some manufacturers say they concentrate on proving a wide range of features rather than on making the machines easy to use. But that gives rise to the question, "Why can't you have features that are easy to use？" The answer is you can.
Good design practice is a mixture of specific procedures and general principles. For a start, designers should build an original model of the machine and try it out on typical members of the public -- not on colleagues in the development laboratory. Simple public trials would quickly reveal many design mistakes. In an ideal world, there would be some ways of controlling quality such as that the VCR must be redesigned repeatedly until, say, 90 per cent of users can work 90 per cent of the features correctly 90 per cent of the time.
According to the passage, before a VCR is sold on the market its original model should be tried out ______.
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