习题练习

[{"id":471,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"在一次环保知识竞赛中，某班级共收集了120份有效问卷。统计结果显示，喜欢垃圾分类宣传活动的学生人数是喜欢节水宣传活动的2倍，而喜欢节水宣传活动的学生比喜欢低碳出行宣传活动的多10人。设喜欢低碳出行宣传活动的学生有x人，则根据题意可列出一元一次方程为：","answer":"A","explanation":"设喜欢低碳出行宣传活动的学生有x人。根据题意，喜欢节水宣传活动的学生比喜欢低碳出行的多10人，因此为(x + 10)人；喜欢垃圾分类宣传活动的学生是喜欢节水宣传的2倍，即为2(x + 10)人。三类人数之和等于总有效问卷数120，因此方程为：x + (x + 10) + 2(x + 10) = 120。选项A正确列出了该方程。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 17:54:03","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"x + (x + 10) + 2(x + 10) = 120","is_correct":1},{"id":"B","content":"x + (x - 10) + 2x = 120","is_correct":0},{"id":"C","content":"x + 2x + (x + 10) = 120","is_correct":0},{"id":"D","content":"x + (x + 10) + 2x = 120","is_correct":0}]},{"id":186,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"小明去文具店买笔记本，每本笔记本的价格是8元。他买了5本，付给收银员50元，应找回多少钱？","answer":"A","explanation":"首先计算小明购买5本笔记本的总花费：8元\/本 × 5本 = 40元。然后从他付的50元中减去总花费：50元 - 40元 = 10元。因此，收银员应找回10元。本题考查的是基本的整数乘法与减法运算，符合七年级数学中关于有理数运算的实际应用要求。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 14:01:19","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"10元","is_correct":1},{"id":"B","content":"12元","is_correct":0},{"id":"C","content":"15元","is_correct":0},{"id":"D","content":"18元","is_correct":0}]},{"id":456,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"某学生调查了班级同学最喜欢的课外活动，并将结果整理成如下条形统计图（图中数据已给出）：阅读12人，运动18人，绘画10人，音乐15人。请问喜欢运动的人数比喜欢绘画的人数多百分之几？","answer":"B","explanation":"题目考查的是数据的收集、整理与描述中的百分比计算。首先确定喜欢运动的人数为18人，喜欢绘画的人数为10人。多出来的人数是18 - 10 = 8人。要求的是‘多百分之几’，即多出的部分占绘画人数的百分比，计算公式为：(多出人数 ÷ 绘画人数) × 100% = (8 ÷ 10) × 100% = 80%。因此正确答案是B。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 17:47:13","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"60%","is_correct":0},{"id":"B","content":"80%","is_correct":1},{"id":"C","content":"50%","is_correct":0},{"id":"D","content":"40%","is_correct":0}]},{"id":20,"subject":"政治","grade":"初一","stage":"初中","type":"选择题","content":"我国的国家性质是？","answer":"C","explanation":"我国是工人阶级领导的、以工农联盟为基础的人民民主专政的社会主义国家。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-08-29 16:33:04","updated_at":"2025-08-29 16:33:04","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"社会主义制度","is_correct":0},{"id":"B","content":"人民代表大会制度","is_correct":0},{"id":"C","content":"人民民主专政","is_correct":1},{"id":"D","content":"多党合作和政治协商制度","is_correct":0}]},{"id":2197,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某学生在练习本上记录了一周内每天的温度变化情况，规定比前一天升高记为正，降低记为负。已知周一到周二的温度变化为 -3℃，周三到周四的温度变化为 +5℃，周五到周六的温度变化为 -2℃。如果周一的起始温度为 10℃，那么周六的温度是多少？","answer":"B","explanation":"从周一的 10℃ 开始，周二变化 -3℃，温度为 10 - 3 = 7℃；周三到周四变化 +5℃，即温度上升 5℃，变为 7 + 5 = 12℃；周五到周六变化 -2℃，即下降 2℃，变为 12 - 2 = 10℃。因此周六的温度是 10℃，正确答案是 B。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-09 14:25:31","updated_at":"2026-01-09 14:25:31","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"8℃","is_correct":0},{"id":"B","content":"10℃","is_correct":1},{"id":"C","content":"12℃","is_correct":0},{"id":"D","content":"14℃","is_correct":0}]},{"id":2217,"subject":"数学","grade":"七年级","stage":"初中","type":"填空题","content":"某学生在记录一周内每天的温度变化时，发现某天的气温比前一天上升了5℃，记作+5℃；第二天又下降了3℃，应记作____℃。","answer":"-3","explanation":"根据正负数表示相反意义的量的知识点，气温上升用正数表示，下降则用负数表示。下降了3℃，应记作-3℃，符合七年级学生对正负数在实际生活中应用的学习要求。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-09 14:27:19","updated_at":"2026-01-09 14:27:19","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[]},{"id":631,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"某班级组织了一次环保知识竞赛，共收集了120份有效问卷。在整理数据时，发现有15%的学生选择了‘垃圾分类’作为最关注的环保问题，有40人选择了‘节约用水’，其余学生选择了‘减少塑料使用’。请问选择‘减少塑料使用’的学生人数是多少？","answer":"C","explanation":"首先计算选择‘垃圾分类’的学生人数：120 × 15% = 120 × 0.15 = 18人。已知选择‘节约用水’的有40人。那么选择‘减少塑料使用’的人数为总人数减去前两项：120 - 18 - 40 = 62人。因此正确答案是C。本题考查数据的收集与整理，涉及百分数的基本计算和简单减法运算，符合七年级数学中‘数据的收集、整理与描述’知识点，难度为简单。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 21:55:43","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"52","is_correct":0},{"id":"B","content":"58","is_correct":0},{"id":"C","content":"62","is_correct":1},{"id":"D","content":"68","is_correct":0}]},{"id":2202,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某学生在一次数学测验中记录了五次测验成绩与班级平均分的差值，分别为：+5，-3，+2，-1，+4。这五次成绩中，高于班级平均分的有几次？","answer":"B","explanation":"正数表示高于班级平均分，负数表示低于平均分。记录中的+5、+2、+4是正数，共3次高于平均分，因此正确答案是B。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-09 14:25:31","updated_at":"2026-01-09 14:25:31","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"2次","is_correct":0},{"id":"B","content":"3次","is_correct":1},{"id":"C","content":"4次","is_correct":0},{"id":"D","content":"5次","is_correct":0}]},{"id":169,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"小明去文具店买笔记本，每本笔记本的价格是8元。他买了5本，付给收银员50元，应找回多少元？","answer":"A","explanation":"首先计算小明购买5本笔记本的总花费：8元\/本 × 5本 = 40元。他付了50元，所以应找回的钱为：50元 - 40元 = 10元。因此正确答案是A。本题考查的是基本的整数乘法和减法运算，属于七年级数学中‘有理数的运算’在实际生活中的应用，难度简单，符合七年级学生的认知水平。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 11:20:33","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"10元","is_correct":1},{"id":"B","content":"12元","is_correct":0},{"id":"C","content":"8元","is_correct":0},{"id":"D","content":"15元","is_correct":0}]},{"id":610,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"某学生在整理班级同学的课外阅读时间时，记录了5位同学每周阅读的小时数分别为：3，5，4，6，2。如果老师要求每位同学的阅读时间都增加相同的整数小时，使得新的数据中位数变为5，那么每位同学至少需要增加多少小时？","answer":"A","explanation":"原始数据为：3，5，4，6，2。先将数据从小到大排序：2，3，4，5，6。当前中位数是中间的数，即4。设每位同学增加x小时（x为正整数），则新数据为：2+x，3+x，4+x，5+x，6+x。排序后仍为：2+x，3+x，4+x，5+x，6+x，中位数是4+x。要求中位数为5，即4 + x = 5，解得x = 1。因此，每位同学至少需要增加1小时。验证：增加1小时后数据为3，4，5，6，7，排序后中位数为5，符合条件。故正确答案为A。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 21:36:13","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"1","is_correct":1},{"id":"B","content":"2","is_correct":0},{"id":"C","content":"3","is_correct":0},{"id":"D","content":"4","is_correct":0}]}]