结构化方法将软件开发分为三个时期，这三个时期是计划期、开发期和 【5】 。
参考答案：运行期
解析： 软件生命周期的瀑布模型典型地刻画了软件生命周期的阶段划分。瀑布模型将软件生命周期划分为8个阶段，各个阶段的任务分别是：问题定义、可行性研究、需求分析、总体设计、详细设计、程序编制，测试和运行、维护。8个阶段又可以归纳为3个时期，即计划期、开发期和运行期。各阶段的工作按顺序开展，形如自上而下的瀑布。
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| When your kids were six or seven, you sent them to school. Did you ever wonder what goes through a teacher's 1 as he or she tries to teach your kids? Did you ever wonder what the teacher 2 from you, the parents? Parents can be 3 or suspicious. They can be of great help to the teacher 4 be in need of help themselves. Some teachers think parents are too 5 on their children. Here is 6 one teacher puts it. "I usually have the 7 of parents coming in and 8 me how much they care about the kids' education and how they really 9 their kids. They tell me they stand and 10 them closely when they do their homework. Sometimes the 11 offer help with the kids' lessons as if they were teachers. They check their school work, and are too sensitive to 12 . They blame the kids on everything having to do 13 school. When a parent asks me how his or her kid is getting on in my class, my answer usually is' Well, you know, he is 14 a good kid. He is fine in my class. Maybe you don't have to be so 15 with your kid.'" Teachers want parents to know that they are professionals at 16 with children. They have 17 many children and even parents. Because of this, teachers can be 18 at educating children. Teachers are 19 that parents want their children to do well, but they know more about what children should be able to do at different ages and 20 . | ||||
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