[{"id":2215,"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℃；而另一天的气温比前一天下降了3℃，应记作____℃。","answer":"-3","explanation":"根据正数和负数表示相反意义的量的规则，气温上升用正数表示，下降则用负数表示。因此，气温下降3℃应记作-3℃。此题考查学生对正负数在实际情境中应用的理解，符合七年级正负数表示相反意义的量的知识点。","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":248,"subject":"数学","grade":"初一","stage":"小学","type":"填空题","content":"出在理解：题目说‘十位数字比个位数字小3’，且交换后大27，数学上所有满足十位=个位-3的两位数都满足差27。但实际计算：如14→41，差27；25→52，差27；36→63，差27；47→74，差27；58→85，差27；69→96，差27。共6个。但题目要求填空一个答案，说明应结合‘中等难度’和‘唯一性’，可能题设隐含常见情况。但原题设计有误？不，重新审视：题目无误，但需指出在七年级范围内，通常取最小或最典型解。但更合理的是题目本意是求所有可能，但填空题只能填一个。因此需修正逻辑。实际上，所有满足‘十位比个位小3’的两位数，交换后差值均为27，这是数学性质。但题目可能期望学生通过设元列方程求解，并得到通解，但填空题需具体值。为避免多解，应增加约束。但原题未增加。因此，选择最常见或最小解。但在标准教学中，此题常以36为例。经核查，原题设计合理，因学生列方程后会发现恒成立，再结合数字范围验证，可能列出多个，但题目‘则原两位数是’暗示唯一，故应修正题设。但为符合要求，采用标准解法：设个位x，十位x-3，原数11x-30，新数11x-3，差27恒成立，x为整数且1≤x-3≤9，0≤x≤9，故x从3到9，但十位至少1，故x-3≥1？不，十位可为0？不，两位数十位不能为0，故x-3≥1 → x≥4。x≤9。所以x=4,5,6,7,8,9。对应14,25,36,47,58,69。但题目应只有一个答案。发现错误：十位数字比个位小3，十位不能为0，故x-3 ≥ 1？不，十位可为1，即x=4，十位=1，可以。但所有都合法。因此","answer":"。问题出在理解：题目说‘十位数字比个位数字小3’，且交换后大27，数学上所有满足十位=个位-3的两位数都满足差27。但实际计算：如14→41，差27；25→52，差27；36→63，差27；47→74，差27；58→85，差27；69→96，差27。共6个。但题目要求填空一个答案，说明应结合‘中等难度’和‘唯一性’，可能题设隐含常见情况。但原题设计有误？不，重新审视：题目无误，但需指出在七年级范围内，通常取最小或最典型解。但更合理的是题目本意是求所有可能，但填空题只能填一个。因此需修正逻辑。实际上，所有满足‘十位比个位小3’的两位数，交换后差值均为27，这是数学性质。但题目可能期望学生通过设元列方程求解，并得到通解，但填空题需具体值。为避免多解，应增加约束。但原题未增加。因此，选择最常见或最小解。但在标准教学中，此题常以36为例。经核查，原题设计合理，因学生列方程后会发现恒成立，再结合数字范围验证，可能列出多个，但题目‘则原两位数是’暗示唯一，故应修正题设。但为符合要求，采用标准解法：设个位x，十位x-3，原数11x-30，新数11x-3，差27恒成立，x为整数且1≤x-3≤9，0≤x≤9，故x从3到9，但十位至少1，故x-3≥1？不，十位可为0？不，两位数十位不能为0，故x-3≥1 → x≥4。x≤9。所以x=4,5,6,7,8,9。对应14,25,36,47,58,69。但题目应只有一个答案。发现错误：十位数字比个位小3，十位不能为0，故x-3 ≥ 1？不，十位可为1，即x=4，十位=1，可以。但所有都合法。因此","explanation":"解析待完善","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"中等","points":1,"is_active":1,"created_at":"2025-12-29 14:54:02","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":1978,"subject":"数学","grade":"九年级","stage":"初中","type":"选择题","content":"某学生在一张纸上画了一个边长为5 cm的正方形，然后以正方形的一个顶点为圆心，以正方形的边长5 cm为半径画了一个扇形。若将该扇形剪下并绕其圆心顺时针旋转60°，则扇形扫过的区域面积是多少？（π取3.14）","answer":"A","explanation":"本题考查扇形旋转过程中扫过区域的面积计算，结合圆与旋转的知识点。初始扇形是以正方形顶点为圆心、半径为5 cm、圆心角为90°的扇形（因为正方形内角为90°）。当该扇形绕圆心顺时针旋转60°时，其扫过的区域是两个扇形之间的环形扇面，即圆心角为60°、半径为5 cm的扇形面积。计算公式为：S = (θ\/360) × πr² = (60\/360) × 3.14 × 5² = (1\/6) × 3.14 × 25 ≈ 13.08 cm²。因此正确答案为A。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-07 15:00:43","updated_at":"2026-01-07 15:00:43","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":"13.08 cm²","is_correct":1},{"id":"B","content":"15.70 cm²","is_correct":0},{"id":"C","content":"18.84 cm²","is_correct":0},{"id":"D","content":"21.98 cm²","is_correct":0}]},{"id":512,"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身高数据时，制作了如下频数分布表：\n\n身高区间（cm） | 频数\n--------------|------\n140～145 | 3\n145～150 | 5\n150～155 | 8\n155～160 | 10\n160～165 | 4\n\n若该班共有30名学生，则身高在150cm及以上的学生人数占全班人数的百分比是多少？","answer":"C","explanation":"首先确定身高在150cm及以上的学生人数。根据表格，150～155cm有8人，155～160cm有10人，160～165cm有4人。将这些频数相加：8 + 10 + 4 = 22人。全班共有30名学生，因此所占百分比为 (22 ÷ 30) × 100% ≈ 73.3%。故正确答案为C。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 18:16:35","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":"66.7%","is_correct":0},{"id":"C","content":"73.3%","is_correct":1},{"id":"D","content":"80%","is_correct":0}]},{"id":504,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"某班级进行了一次数学测验，老师将成绩整理后绘制成频数分布直方图，发现成绩在80分到90分之间的学生人数最多。这说明该分数段的什么统计量最大？","answer":"C","explanation":"题目中提到“成绩在80分到90分之间的学生人数最多”，这表示该分数段出现的次数最多。在统计学中，一组数据中出现次数最多的数值称为众数。因此，80分到90分这个区间对应的众数最大。平均数是所有数据的总和除以个数，中位数是数据排序后位于中间的数，极差是最大值与最小值之差，它们都不能直接由‘人数最多’得出。故正确答案为C。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 18:10:48","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":"平均数","is_correct":0},{"id":"B","content":"中位数","is_correct":0},{"id":"C","content":"众数","is_correct":1},{"id":"D","content":"极差","is_correct":0}]},{"id":560,"subject":"数学","grade":"初一","stage":"小学","type":"选择题","content":"102千克","answer":"待完善","explanation":"解析待完善","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 19:22:34","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":18,"subject":"地理","grade":"初一","stage":"初中","type":"选择题","content":"世界上面积最大的洲是？","answer":"A","explanation":"亚洲是世界上面积最大、人口最多的大洲。","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":"亚洲","is_correct":1},{"id":"B","content":"非洲","is_correct":0},{"id":"C","content":"北美洲","is_correct":0},{"id":"D","content":"南美洲","is_correct":0}]},{"id":328,"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身高数据时，制作了如下频数分布表。已知身高在150～160cm的学生人数占总人数的40%，总人数为50人，则身高在150～160cm的学生有多少人？","answer":"B","explanation":"题目中已知总人数为50人，身高在150～160cm的学生占总人数的40%。要求这部分学生的人数，只需计算50的40%是多少。计算过程为：50 × 40% = 50 × 0.4 = 20。因此，身高在150～160cm的学生有20人。该题考查的是数据的收集、整理与描述中关于百分比和频数的实际应用，属于简单难度，符合七年级数学课程要求。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 15:39:01","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":"15","is_correct":0},{"id":"B","content":"20","is_correct":1},{"id":"C","content":"25","is_correct":0},{"id":"D","content":"30","is_correct":0}]},{"id":2190,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某学生在一条东西方向的直线上做实验，规定向东为正方向。他从原点出发，先向东走了5米，记作+5米，然后向西走了8米。此时他所在的位置应记作多少米？","answer":"D","explanation":"该学生从原点出发，向东走5米到达+5米的位置，再向西走8米，相当于从+5米减去8米，即5 - 8 = -3米。因此，他最终位置应记作-3米。选项D正确。","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":"+13米","is_correct":0},{"id":"B","content":"+3米","is_correct":0},{"id":"C","content":"-3米","is_correct":0},{"id":"D","content":"-13米","is_correct":1}]},{"id":345,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"在平面直角坐标系中，点 A 的坐标是 (3, 4)，点 B 的坐标是 (3, -2)。这两点之间的距离是多少？","answer":"A","explanation":"点 A 和点 B 的横坐标相同，都是 3，说明它们位于同一条竖直线上。两点之间的距离等于它们纵坐标之差的绝对值。计算：|4 - (-2)| = |4 + 2| = |6| = 6。因此，两点之间的距离是 6。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 15:41:02","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":"6","is_correct":1},{"id":"B","content":"5","is_correct":0},{"id":"C","content":"7","is_correct":0},{"id":"D","content":"8","is_correct":0}]}]