As information systems are complex and multifaceted,failure(and success)can be manifested(表现，体现)in many ways.There are two important ways of looking at information systems that lead to different(71)ofconsidering their success or failure.
In the straightforward case, an information system can be considered as a project that is instigated,specified, designed and eventually implemented and maintained. It goes through a life cycle like the one described above.When big,high profile information system(72)fail, theyattract significant amounts of publicity, especially if theyare in the public sector, and their consequences are often dramatic and far-reaching.
At another extreme,there are information systems that form sets of subsystems that work together to deliver an overall information system. The subsystems may be modified and updated. new items may be introduced and redundant ones removed.People may tak about this being a (73)information system, and it may be criticized or deemed to bea(74),but neither it nor its predecessors need ever have been designed as a complete whole. Evolved information systems may develop slowly over a long period of time, sometimes changing imperceptibly(极微小地)and sometimes being the subject of fairly major modifications. Such systems can fail catastrophically(灾难性地),but it is often the case that they(75)become unable to cope with the demands placed upon them untilifnot modifiedthey reach a point where they start to cause serious harm to the activities they were designed to support.
