[填空题]Video recorders and photocopiers, even ticket machines on the railways, often seem unnecessarily difficult to use. Last December I bought myself a Video cassette recorder{{U}} (36) {{/U}}as "simple to use!’. In the first three weeks I failed{{U}} (37) {{/U}}to program the machine to record from the TV, and after months of practice I still made mistakes. I am not alone. According to a{{U}} (38) {{/U}}last year by Ferguson, the British manufacturer, more than one in four VCR owners never use the timer on their machines to record a programmer: 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{{U}} (39) {{/U}}to use if the problems are so obvious First, the problems we notice are not obvious to{{U}} (40) {{/U}}minded designers with years of experience and trained to understand how{{U}} (41) {{/U}}work. Secondly,. designers tend to add one or two features at a time to each model,{{U}} (