[填空题]（中国矿业大学2009年试题） Solving a problem can be broken into several steps. First, the problem must be identified correctly. Psychologists refer【1】this step as problem representation. For many problems, figuring【2】which information is relevant and which is extraneous can be difficult and can interfere【3】arriving at a good solution. Clearly, before a problem can be solved, it must be obvious【4】the problem is, however, this is not as easy【5】it might seem. One obstacle to efficient problem representation is functional fixedness, that is, allowing preconceived notions and even prejudices to color the facts. Most people tend【6】see objects and events in certain fixed ways, and by being inflexible in viewing the problem, they may be unable to notice the tools【7】the solution. Once the problem is identified accurately,【8】, the second step consists【9】considering the alternatives for a solution. A common way to evaluate alternatives is to write them【10】and then make a list【11】advantages and disadvantages for each solution. Here again, people may be limited by prior experiences. Often people adopt mental sets【12】lead them to the same problem-solving strategies that were successful for problems【13】the past. Although that can be helpful most【14】the time, sometimes a new situation requires a different strategy.【15】that case, the mental set must be abandoned, and new alternatives must be explored.【13】