"""知识竞速 题库 — 科学 (science). Curated, fact-checked, single-answer."""
from __future__ import annotations

QUESTIONS: list[dict] = [
    {"prompt": "光在真空中的速度约为？", "options": [{"key":"A","text":"3×10⁵ km/s"},{"key":"B","text":"3×10⁸ km/s"},{"key":"C","text":"3×10⁶ m/s"},{"key":"D","text":"3×10⁴ km/s"}], "correct_key": "A", "explanation": "光速约每秒 30 万公里，即 3×10⁵ km/s。", "category": "science"},
    {"prompt": "水的化学式是什么？", "options": [{"key":"A","text":"CO₂"},{"key":"B","text":"H₂O"},{"key":"C","text":"O₂"},{"key":"D","text":"NaCl"}], "correct_key": "B", "explanation": "水由两个氢原子和一个氧原子组成，化学式为 H₂O。", "category": "science"},
    {"prompt": "人体正常体温约为多少摄氏度？", "options": [{"key":"A","text":"30℃"},{"key":"B","text":"42℃"},{"key":"C","text":"37℃"},{"key":"D","text":"45℃"}], "correct_key": "C", "explanation": "健康成年人的正常体温约为 37℃。", "category": "science"},
    {"prompt": "太阳系中体积最大的行星是？", "options": [{"key":"A","text":"地球"},{"key":"B","text":"火星"},{"key":"C","text":"土星"},{"key":"D","text":"木星"}], "correct_key": "D", "explanation": "木星是太阳系中体积和质量最大的行星。", "category": "science"},
    {"prompt": "植物进行光合作用主要吸收哪种气体？", "options": [{"key":"A","text":"二氧化碳"},{"key":"B","text":"氧气"},{"key":"C","text":"氮气"},{"key":"D","text":"氢气"}], "correct_key": "A", "explanation": "光合作用吸收二氧化碳并释放氧气。", "category": "science"},
    {"prompt": "元素周期表中原子序数为 1 的元素是？", "options": [{"key":"A","text":"氦"},{"key":"B","text":"氢"},{"key":"C","text":"锂"},{"key":"D","text":"碳"}], "correct_key": "B", "explanation": "氢的原子序数为 1，是最轻的元素。", "category": "science"},
    {"prompt": "一年中地球绕太阳公转一周大约需要多少天？", "options": [{"key":"A","text":"30 天"},{"key":"B","text":"100 天"},{"key":"C","text":"365 天"},{"key":"D","text":"500 天"}], "correct_key": "C", "explanation": "地球绕太阳公转一周约 365 天，即一年。", "category": "science"},
    {"prompt": "声音在下列哪种介质中传播最快？", "options": [{"key":"A","text":"空气"},{"key":"B","text":"水"},{"key":"C","text":"真空"},{"key":"D","text":"钢铁"}], "correct_key": "D", "explanation": "声音在固体（如钢铁）中传播速度最快，在真空中无法传播。", "category": "science"},
    {"prompt": "人体最大的器官是？", "options": [{"key":"A","text":"皮肤"},{"key":"B","text":"心脏"},{"key":"C","text":"肝脏"},{"key":"D","text":"大脑"}], "correct_key": "A", "explanation": "皮肤是人体面积和重量最大的器官。", "category": "science"},
    {"prompt": "DNA 的中文全称是？", "options": [{"key":"A","text":"核糖核酸"},{"key":"B","text":"脱氧核糖核酸"},{"key":"C","text":"氨基酸"},{"key":"D","text":"蛋白质"}], "correct_key": "B", "explanation": "DNA 即脱氧核糖核酸，携带遗传信息。", "category": "science"},
    {"prompt": "地球大气中含量最多的气体是？", "options": [{"key":"A","text":"氧气"},{"key":"B","text":"二氧化碳"},{"key":"C","text":"氮气"},{"key":"D","text":"氩气"}], "correct_key": "C", "explanation": "氮气约占大气体积的 78%，是含量最多的气体。", "category": "science"},
    {"prompt": "标准大气压下水的沸点是多少摄氏度？", "options": [{"key":"A","text":"50℃"},{"key":"B","text":"150℃"},{"key":"C","text":"80℃"},{"key":"D","text":"100℃"}], "correct_key": "D", "explanation": "标准大气压下水在 100℃ 沸腾。", "category": "science"},
    {"prompt": "牛顿第一定律又称为？", "options": [{"key":"A","text":"惯性定律"},{"key":"B","text":"万有引力定律"},{"key":"C","text":"作用力与反作用力定律"},{"key":"D","text":"能量守恒定律"}], "correct_key": "A", "explanation": "牛顿第一定律描述物体保持原有运动状态的惯性，又称惯性定律。", "category": "science"},
    {"prompt": "血液中负责运输氧气的细胞是？", "options": [{"key":"A","text":"白细胞"},{"key":"B","text":"红细胞"},{"key":"C","text":"血小板"},{"key":"D","text":"淋巴细胞"}], "correct_key": "B", "explanation": "红细胞含血红蛋白，负责运输氧气。", "category": "science"},
    {"prompt": "离太阳最近的行星是？", "options": [{"key":"A","text":"金星"},{"key":"B","text":"地球"},{"key":"C","text":"水星"},{"key":"D","text":"火星"}], "correct_key": "C", "explanation": "水星是距离太阳最近的行星。", "category": "science"},
    {"prompt": "食盐的主要化学成分是？", "options": [{"key":"A","text":"碳酸钙"},{"key":"B","text":"硫酸铜"},{"key":"C","text":"氢氧化钠"},{"key":"D","text":"氯化钠"}], "correct_key": "D", "explanation": "食盐的主要成分是氯化钠（NaCl）。", "category": "science"},
    {"prompt": "圆的周长与直径的比值是哪个常数？", "options": [{"key":"A","text":"π"},{"key":"B","text":"e"},{"key":"C","text":"φ"},{"key":"D","text":"√2"}], "correct_key": "A", "explanation": "圆周率 π 是圆周长与直径的比值，约为 3.14159。", "category": "science"},
    {"prompt": "下列哪位科学家提出了相对论？", "options": [{"key":"A","text":"牛顿"},{"key":"B","text":"爱因斯坦"},{"key":"C","text":"伽利略"},{"key":"D","text":"达尔文"}], "correct_key": "B", "explanation": "阿尔伯特·爱因斯坦提出了狭义与广义相对论。", "category": "science"},
    {"prompt": "人体内正常的染色体有多少条？", "options": [{"key":"A","text":"23 条"},{"key":"B","text":"44 条"},{"key":"C","text":"46 条"},{"key":"D","text":"48 条"}], "correct_key": "C", "explanation": "人体正常体细胞含有 23 对共 46 条染色体。", "category": "science"},
    {"prompt": "彩虹是由于阳光经过什么形成的？", "options": [{"key":"A","text":"燃烧"},{"key":"B","text":"磁场"},{"key":"C","text":"化学反应"},{"key":"D","text":"反射与色散"}], "correct_key": "D", "explanation": "阳光在水滴中折射、反射并色散形成彩虹。", "category": "science"},
    {"prompt": "以下哪种物质是导电性最好的金属？", "options": [{"key":"A","text":"银"},{"key":"B","text":"铁"},{"key":"C","text":"铝"},{"key":"D","text":"金"}], "correct_key": "A", "explanation": "银是常温下导电性最好的金属。", "category": "science"},
    {"prompt": "地球上潮汐现象主要由什么引起？", "options": [{"key":"A","text":"风力"},{"key":"B","text":"月球引力"},{"key":"C","text":"地球自转"},{"key":"D","text":"太阳黑子"}], "correct_key": "B", "explanation": "潮汐主要由月球（及太阳）的引力引起。", "category": "science"},
    {"prompt": "光合作用主要发生在植物细胞的哪个结构中？", "options": [{"key":"A","text":"线粒体"},{"key":"B","text":"细胞核"},{"key":"C","text":"叶绿体"},{"key":"D","text":"液泡"}], "correct_key": "C", "explanation": "叶绿体中的叶绿素负责光合作用。", "category": "science"},
    {"prompt": "1 千米等于多少米？", "options": [{"key":"A","text":"100 米"},{"key":"B","text":"10000 米"},{"key":"C","text":"10 米"},{"key":"D","text":"1000 米"}], "correct_key": "D", "explanation": "1 千米（公里）等于 1000 米。", "category": "science"},
    {"prompt": "下列哪种气体会导致温室效应加剧？", "options": [{"key":"A","text":"二氧化碳"},{"key":"B","text":"氮气"},{"key":"C","text":"氧气"},{"key":"D","text":"氩气"}], "correct_key": "A", "explanation": "二氧化碳是主要的温室气体之一。", "category": "science"},
    {"prompt": "维生素 C 缺乏会导致哪种疾病？", "options": [{"key":"A","text":"夜盲症"},{"key":"B","text":"坏血病"},{"key":"C","text":"佝偻病"},{"key":"D","text":"脚气病"}], "correct_key": "B", "explanation": "长期缺乏维生素 C 会引起坏血病。", "category": "science"},
    {"prompt": "月球是地球的什么？", "options": [{"key":"A","text":"行星"},{"key":"B","text":"恒星"},{"key":"C","text":"卫星"},{"key":"D","text":"彗星"}], "correct_key": "C", "explanation": "月球是地球唯一的天然卫星。", "category": "science"},
    {"prompt": "下列哪种元素常温下是液态？", "options": [{"key":"A","text":"铁"},{"key":"B","text":"铜"},{"key":"C","text":"钠"},{"key":"D","text":"汞"}], "correct_key": "D", "explanation": "汞（水银）是常温下唯一呈液态的金属。", "category": "science"},
    {"prompt": "人体消化淀粉最初发生在哪里？", "options": [{"key":"A","text":"口腔"},{"key":"B","text":"胃"},{"key":"C","text":"小肠"},{"key":"D","text":"大肠"}], "correct_key": "A", "explanation": "口腔唾液中的淀粉酶开始分解淀粉。", "category": "science"},
    {"prompt": "地球自转一周大约需要多长时间？", "options": [{"key":"A","text":"12 小时"},{"key":"B","text":"24 小时"},{"key":"C","text":"48 小时"},{"key":"D","text":"1 个月"}], "correct_key": "B", "explanation": "地球自转一周约 24 小时，形成昼夜交替。", "category": "science"},
    {"prompt": "下列哪个是质数？", "options": [{"key":"A","text":"9"},{"key":"B","text":"15"},{"key":"C","text":"17"},{"key":"D","text":"21"}], "correct_key": "C", "explanation": "17 只能被 1 和自身整除，是质数。", "category": "science"},
    {"prompt": "空气中氧气约占体积的百分之几？", "options": [{"key":"A","text":"50%"},{"key":"B","text":"78%"},{"key":"C","text":"10%"},{"key":"D","text":"21%"}], "correct_key": "D", "explanation": "氧气约占大气体积的 21%。", "category": "science"},
    {"prompt": "提出进化论的科学家是？", "options": [{"key":"A","text":"达尔文"},{"key":"B","text":"孟德尔"},{"key":"C","text":"巴斯德"},{"key":"D","text":"林奈"}], "correct_key": "A", "explanation": "查尔斯·达尔文提出以自然选择为核心的进化论。", "category": "science"},
    {"prompt": "电流的国际单位是？", "options": [{"key":"A","text":"伏特"},{"key":"B","text":"安培"},{"key":"C","text":"欧姆"},{"key":"D","text":"瓦特"}], "correct_key": "B", "explanation": "电流的国际单位是安培（A）。", "category": "science"},
    {"prompt": "下列哪种动物是哺乳动物？", "options": [{"key":"A","text":"鲨鱼"},{"key":"B","text":"鳄鱼"},{"key":"C","text":"鲸鱼"},{"key":"D","text":"章鱼"}], "correct_key": "C", "explanation": "鲸鱼用肺呼吸、胎生哺乳，是哺乳动物。", "category": "science"},
    {"prompt": "金刚石和石墨都是由什么元素组成的？", "options": [{"key":"A","text":"硅"},{"key":"B","text":"氧"},{"key":"C","text":"铁"},{"key":"D","text":"碳"}], "correct_key": "D", "explanation": "金刚石与石墨都是碳的同素异形体。", "category": "science"},
    {"prompt": "地震的强度常用什么来衡量？", "options": [{"key":"A","text":"里氏震级"},{"key":"B","text":"分贝"},{"key":"C","text":"开尔文"},{"key":"D","text":"帕斯卡"}], "correct_key": "A", "explanation": "地震释放能量常用里氏震级等标度衡量。", "category": "science"},
    {"prompt": "人体呼吸时主要排出哪种气体？", "options": [{"key":"A","text":"氮气"},{"key":"B","text":"二氧化碳"},{"key":"C","text":"氢气"},{"key":"D","text":"臭氧"}], "correct_key": "B", "explanation": "呼吸作用产生并排出二氧化碳。", "category": "science"},
    {"prompt": "太阳主要由哪两种元素组成？", "options": [{"key":"A","text":"氧和碳"},{"key":"B","text":"铁和镍"},{"key":"C","text":"氢和氦"},{"key":"D","text":"氮和氧"}], "correct_key": "C", "explanation": "太阳主要由氢和氦构成，通过核聚变发光发热。", "category": "science"},
    {"prompt": "下列哪个器官负责过滤血液并生成尿液？", "options": [{"key":"A","text":"肝脏"},{"key":"B","text":"脾脏"},{"key":"C","text":"胰腺"},{"key":"D","text":"肾脏"}], "correct_key": "D", "explanation": "肾脏过滤血液中的废物并形成尿液。", "category": "science"},
    {"prompt": "水结成冰时体积会发生什么变化？", "options": [{"key":"A","text":"膨胀"},{"key":"B","text":"缩小"},{"key":"C","text":"不变"},{"key":"D","text":"先缩后胀"}], "correct_key": "A", "explanation": "水结冰时体积膨胀，密度减小，因此冰能浮在水面。", "category": "science"},
    {"prompt": "一个直角三角形中，两直角边平方和等于什么的平方？", "options": [{"key":"A","text":"任一直角边"},{"key":"B","text":"斜边"},{"key":"C","text":"周长"},{"key":"D","text":"面积"}], "correct_key": "B", "explanation": "勾股定理：两直角边平方和等于斜边平方。", "category": "science"},
    {"prompt": "细胞学说认为一切生物都由什么构成？", "options": [{"key":"A","text":"分子"},{"key":"B","text":"原子"},{"key":"C","text":"细胞"},{"key":"D","text":"组织"}], "correct_key": "C", "explanation": "细胞学说指出细胞是生物体结构和功能的基本单位。", "category": "science"},
    {"prompt": "以下哪种波长的可见光频率最高？", "options": [{"key":"A","text":"红光"},{"key":"B","text":"绿光"},{"key":"C","text":"黄光"},{"key":"D","text":"紫光"}], "correct_key": "D", "explanation": "紫光波长最短、频率最高。", "category": "science"},
    {"prompt": "力的国际单位是？", "options": [{"key":"A","text":"牛顿"},{"key":"B","text":"焦耳"},{"key":"C","text":"帕斯卡"},{"key":"D","text":"瓦特"}], "correct_key": "A", "explanation": "力的国际单位是牛顿（N）。", "category": "science"},
    {"prompt": "人体骨骼中最长的骨头是？", "options": [{"key":"A","text":"肱骨"},{"key":"B","text":"股骨"},{"key":"C","text":"胫骨"},{"key":"D","text":"肋骨"}], "correct_key": "B", "explanation": "股骨（大腿骨）是人体最长最强壮的骨头。", "category": "science"},
    {"prompt": "下列哪种现象说明光沿直线传播？", "options": [{"key":"A","text":"彩虹"},{"key":"B","text":"海市蜃楼"},{"key":"C","text":"影子"},{"key":"D","text":"凸透镜成像"}], "correct_key": "C", "explanation": "影子的形成说明光在均匀介质中沿直线传播。", "category": "science"},
    {"prompt": "地球上海洋约占地表面积的多少？", "options": [{"key":"A","text":"约三分之一"},{"key":"B","text":"约一半"},{"key":"C","text":"约九成"},{"key":"D","text":"约七成"}], "correct_key": "D", "explanation": "海洋约占地球表面积的 71%，约七成。", "category": "science"},
    {"prompt": "以下哪种粒子带负电？", "options": [{"key":"A","text":"电子"},{"key":"B","text":"质子"},{"key":"C","text":"中子"},{"key":"D","text":"光子"}], "correct_key": "A", "explanation": "电子带负电，质子带正电，中子不带电。", "category": "science"},
    {"prompt": "植物根部主要吸收什么？", "options": [{"key":"A","text":"阳光"},{"key":"B","text":"水和无机盐"},{"key":"C","text":"二氧化碳"},{"key":"D","text":"氧气"}], "correct_key": "B", "explanation": "根部主要吸收水分和溶解的无机盐。", "category": "science"},
    {"prompt": "0℃ 相当于多少开尔文？", "options": [{"key":"A","text":"0 K"},{"key":"B","text":"100 K"},{"key":"C","text":"273 K"},{"key":"D","text":"373 K"}], "correct_key": "C", "explanation": "0℃ 约等于 273.15 K。", "category": "science"},
    {"prompt": "下列哪颗行星被称为「红色行星」？", "options": [{"key":"A","text":"金星"},{"key":"B","text":"木星"},{"key":"C","text":"水星"},{"key":"D","text":"火星"}], "correct_key": "D", "explanation": "火星表面富含氧化铁呈红色，被称为红色行星。", "category": "science"},
    {"prompt": "酸性溶液的 pH 值范围是？", "options": [{"key":"A","text":"小于 7"},{"key":"B","text":"大于 7"},{"key":"C","text":"等于 7"},{"key":"D","text":"等于 14"}], "correct_key": "A", "explanation": "pH 小于 7 为酸性，等于 7 为中性，大于 7 为碱性。", "category": "science"},
    {"prompt": "遗传学之父指的是哪位科学家？", "options": [{"key":"A","text":"达尔文"},{"key":"B","text":"孟德尔"},{"key":"C","text":"沃森"},{"key":"D","text":"巴斯德"}], "correct_key": "B", "explanation": "孟德尔通过豌豆实验发现遗传规律，被誉为遗传学之父。", "category": "science"},
    {"prompt": "能量的国际单位是？", "options": [{"key":"A","text":"瓦特"},{"key":"B","text":"牛顿"},{"key":"C","text":"焦耳"},{"key":"D","text":"安培"}], "correct_key": "C", "explanation": "能量（功）的国际单位是焦耳（J）。", "category": "science"},
    {"prompt": "下列哪种血型被称为「万能供血者」（在红细胞层面）？", "options": [{"key":"A","text":"A 型"},{"key":"B","text":"B 型"},{"key":"C","text":"AB 型"},{"key":"D","text":"O 型"}], "correct_key": "D", "explanation": "O 型红细胞无 A、B 抗原，常被称为万能供血者。", "category": "science"},
    {"prompt": "地球内部结构从外到内正确的顺序是？", "options": [{"key":"A","text":"地壳—地幔—地核"},{"key":"B","text":"地核—地幔—地壳"},{"key":"C","text":"地幔—地壳—地核"},{"key":"D","text":"地壳—地核—地幔"}], "correct_key": "A", "explanation": "地球由外到内依次为地壳、地幔、地核。", "category": "science"},
    {"prompt": "以下哪种简单机械能省力？", "options": [{"key":"A","text":"定滑轮"},{"key":"B","text":"动滑轮"},{"key":"C","text":"都不省力"},{"key":"D","text":"两者都省力"}], "correct_key": "B", "explanation": "动滑轮能省力（但费距离），定滑轮只改变力的方向。", "category": "science"},
    {"prompt": "以下哪种维生素主要由皮肤在阳光照射下合成？", "options": [{"key":"A","text":"维生素 A"},{"key":"B","text":"维生素 C"},{"key":"C","text":"维生素 D"},{"key":"D","text":"维生素 K"}], "correct_key": "C", "explanation": "皮肤在紫外线照射下可合成维生素 D。", "category": "science"},
    {"prompt": "两个奇数相加的结果一定是？", "options": [{"key":"A","text":"奇数"},{"key":"B","text":"质数"},{"key":"C","text":"无法确定"},{"key":"D","text":"偶数"}], "correct_key": "D", "explanation": "两个奇数之和一定是偶数。", "category": "science"},
    {"prompt": "人类的听觉器官是？", "options": [{"key":"A","text":"耳"},{"key":"B","text":"眼"},{"key":"C","text":"鼻"},{"key":"D","text":"舌"}], "correct_key": "A", "explanation": "耳是接收声音、产生听觉的器官。", "category": "science"},
    {"prompt": "下列哪种能源属于可再生能源？", "options": [{"key":"A","text":"煤炭"},{"key":"B","text":"太阳能"},{"key":"C","text":"石油"},{"key":"D","text":"天然气"}], "correct_key": "B", "explanation": "太阳能可持续获取，属于可再生能源。", "category": "science"},
    {"prompt": "一个物体不受外力时会保持什么状态？", "options": [{"key":"A","text":"加速"},{"key":"B","text":"减速"},{"key":"C","text":"静止或匀速直线运动"},{"key":"D","text":"圆周运动"}], "correct_key": "C", "explanation": "根据惯性定律，不受外力物体保持静止或匀速直线运动。", "category": "science"},
    {"prompt": "人体内负责分泌胰岛素的器官是？", "options": [{"key":"A","text":"肝脏"},{"key":"B","text":"肾脏"},{"key":"C","text":"胃"},{"key":"D","text":"胰腺"}], "correct_key": "D", "explanation": "胰腺中的胰岛细胞分泌胰岛素，调节血糖。", "category": "science"},
    {"prompt": "自然界中最硬的天然物质是？", "options": [{"key":"A","text":"金刚石"},{"key":"B","text":"石英"},{"key":"C","text":"钢"},{"key":"D","text":"花岗岩"}], "correct_key": "A", "explanation": "金刚石是已知天然物质中硬度最高的。", "category": "science"},
    {"prompt": "下列哪种现象属于化学变化？", "options": [{"key":"A","text":"冰融化"},{"key":"B","text":"铁生锈"},{"key":"C","text":"水蒸发"},{"key":"D","text":"玻璃破碎"}], "correct_key": "B", "explanation": "铁生锈生成了新物质氧化铁，属于化学变化。", "category": "science"},
    {"prompt": "光年是测量什么的单位？", "options": [{"key":"A","text":"时间"},{"key":"B","text":"速度"},{"key":"C","text":"距离"},{"key":"D","text":"亮度"}], "correct_key": "C", "explanation": "光年是光在一年内传播的距离，是长度单位。", "category": "science"},
    {"prompt": "下列哪种动物属于两栖动物？", "options": [{"key":"A","text":"蛇"},{"key":"B","text":"海豚"},{"key":"C","text":"麻雀"},{"key":"D","text":"青蛙"}], "correct_key": "D", "explanation": "青蛙幼体用鳃、成体用肺呼吸，是典型两栖动物。", "category": "science"},
    {"prompt": "功率的国际单位是？", "options": [{"key":"A","text":"瓦特"},{"key":"B","text":"焦耳"},{"key":"C","text":"牛顿"},{"key":"D","text":"伏特"}], "correct_key": "A", "explanation": "功率的国际单位是瓦特（W），即每秒 1 焦耳。", "category": "science"},
    {"prompt": "以下哪个是太阳系中的矮行星？", "options": [{"key":"A","text":"海王星"},{"key":"B","text":"冥王星"},{"key":"C","text":"天王星"},{"key":"D","text":"土星"}], "correct_key": "B", "explanation": "冥王星在 2006 年被重新归类为矮行星。", "category": "science"},
    {"prompt": "植物通过什么结构进行气体交换？", "options": [{"key":"A","text":"根毛"},{"key":"B","text":"茎"},{"key":"C","text":"气孔"},{"key":"D","text":"花瓣"}], "correct_key": "C", "explanation": "叶片上的气孔是植物气体交换的主要通道。", "category": "science"},
    {"prompt": "1 摄氏度的温度变化等于多少开尔文的变化？", "options": [{"key":"A","text":"273 K"},{"key":"B","text":"100 K"},{"key":"C","text":"0 K"},{"key":"D","text":"1 K"}], "correct_key": "D", "explanation": "摄氏度与开尔文的刻度间隔相同，1℃ 变化等于 1 K 变化。", "category": "science"},
    {"prompt": "下列哪种气体能使带火星的木条复燃？", "options": [{"key":"A","text":"氧气"},{"key":"B","text":"氮气"},{"key":"C","text":"二氧化碳"},{"key":"D","text":"氢气"}], "correct_key": "A", "explanation": "氧气支持燃烧，能使带火星的木条复燃。", "category": "science"},
    {"prompt": "人体中枢神经系统由什么组成？", "options": [{"key":"A","text":"心脏和血管"},{"key":"B","text":"脑和脊髓"},{"key":"C","text":"肺和气管"},{"key":"D","text":"肝和胆"}], "correct_key": "B", "explanation": "中枢神经系统由脑和脊髓构成。", "category": "science"},
    {"prompt": "水在多少摄氏度时密度最大？", "options": [{"key":"A","text":"0℃"},{"key":"B","text":"100℃"},{"key":"C","text":"4℃"},{"key":"D","text":"-4℃"}], "correct_key": "C", "explanation": "水在约 4℃ 时密度最大。", "category": "science"},
    {"prompt": "下列哪个数是最小的正整数？", "options": [{"key":"A","text":"0"},{"key":"B","text":"-1"},{"key":"C","text":"2"},{"key":"D","text":"1"}], "correct_key": "D", "explanation": "1 是最小的正整数（0 既不是正数也不是负数）。", "category": "science"},
    {"prompt": "太阳能电池主要利用哪种效应发电？", "options": [{"key":"A","text":"光电效应"},{"key":"B","text":"热电效应"},{"key":"C","text":"压电效应"},{"key":"D","text":"磁电效应"}], "correct_key": "A", "explanation": "太阳能电池利用半导体的光生伏特（光电）效应发电。", "category": "science"},
    {"prompt": "下列哪个是人体最小的骨头（位于耳中）？", "options": [{"key":"A","text":"股骨"},{"key":"B","text":"镫骨"},{"key":"C","text":"锁骨"},{"key":"D","text":"尾骨"}], "correct_key": "B", "explanation": "镫骨位于中耳，是人体最小的骨头。", "category": "science"},
    {"prompt": "地球的天然卫星月球围绕地球公转一周约需要多长时间？", "options": [{"key":"A","text":"约 1 天"},{"key":"B","text":"约 100 天"},{"key":"C","text":"约 27 天"},{"key":"D","text":"约 365 天"}], "correct_key": "C", "explanation": "月球绕地球公转一周约 27.3 天。", "category": "science"},
    {"prompt": "下列哪种物质的 pH 呈碱性？", "options": [{"key":"A","text":"柠檬汁"},{"key":"B","text":"食醋"},{"key":"C","text":"纯水"},{"key":"D","text":"肥皂水"}], "correct_key": "D", "explanation": "肥皂水呈碱性，pH 大于 7。", "category": "science"},
    {"prompt": "构成蛋白质的基本单位是？", "options": [{"key":"A","text":"氨基酸"},{"key":"B","text":"葡萄糖"},{"key":"C","text":"脂肪酸"},{"key":"D","text":"核苷酸"}], "correct_key": "A", "explanation": "氨基酸是构成蛋白质的基本单位。", "category": "science"},
    {"prompt": "下列哪种波不属于电磁波？", "options": [{"key":"A","text":"无线电波"},{"key":"B","text":"声波"},{"key":"C","text":"可见光"},{"key":"D","text":"X 射线"}], "correct_key": "B", "explanation": "声波是机械波，需要介质传播，不属于电磁波。", "category": "science"},
    {"prompt": "地球上四季变化主要是由什么造成的？", "options": [{"key":"A","text":"地球自转"},{"key":"B","text":"月球引力"},{"key":"C","text":"地轴倾斜与公转"},{"key":"D","text":"太阳黑子"}], "correct_key": "C", "explanation": "地轴倾斜加上地球公转导致太阳直射点移动，形成四季。", "category": "science"},
    {"prompt": "以下哪个化学符号代表氧？", "options": [{"key":"A","text":"Au"},{"key":"B","text":"H"},{"key":"C","text":"C"},{"key":"D","text":"O"}], "correct_key": "D", "explanation": "O 是氧元素的化学符号。", "category": "science"},
    {"prompt": "生物分类中最基本的单位是？", "options": [{"key":"A","text":"种"},{"key":"B","text":"界"},{"key":"C","text":"门"},{"key":"D","text":"纲"}], "correct_key": "A", "explanation": "种是生物分类的最基本单位。", "category": "science"},
    {"prompt": "以下哪个是速度的单位？", "options": [{"key":"A","text":"千克"},{"key":"B","text":"米/秒"},{"key":"C","text":"焦耳"},{"key":"D","text":"牛顿"}], "correct_key": "B", "explanation": "米每秒（m/s）是速度的常用单位。", "category": "science"},
    {"prompt": "彗星靠近太阳时会出现明显的什么？", "options": [{"key":"A","text":"光环"},{"key":"B","text":"极光"},{"key":"C","text":"彗尾"},{"key":"D","text":"日冕"}], "correct_key": "C", "explanation": "彗星接近太阳时受太阳风与辐射作用形成彗尾。", "category": "science"},
    {"prompt": "人体内红细胞主要在哪里生成？", "options": [{"key":"A","text":"心脏"},{"key":"B","text":"肝脏"},{"key":"C","text":"肺"},{"key":"D","text":"骨髓"}], "correct_key": "D", "explanation": "成年人的红细胞主要在红骨髓中生成。", "category": "science"},
    {"prompt": "下列哪种反应会释放热量？", "options": [{"key":"A","text":"放热反应"},{"key":"B","text":"吸热反应"},{"key":"C","text":"光解反应"},{"key":"D","text":"电解反应"}], "correct_key": "A", "explanation": "放热反应（如燃烧）向环境释放热量。", "category": "science"},
    {"prompt": "半径为 r 的圆，其面积公式是？", "options": [{"key":"A","text":"2πr"},{"key":"B","text":"πr²"},{"key":"C","text":"πd"},{"key":"D","text":"4πr²"}], "correct_key": "B", "explanation": "圆的面积等于 πr²。", "category": "science"},
    {"prompt": "以下哪种元素是人体骨骼和牙齿的重要组成成分？", "options": [{"key":"A","text":"钾"},{"key":"B","text":"钠"},{"key":"C","text":"钙"},{"key":"D","text":"铁"}], "correct_key": "C", "explanation": "钙是骨骼和牙齿的主要矿物质成分。", "category": "science"},
    {"prompt": "下列哪种设备可将电能转化为机械能？", "options": [{"key":"A","text":"发电机"},{"key":"B","text":"变压器"},{"key":"C","text":"电池"},{"key":"D","text":"电动机"}], "correct_key": "D", "explanation": "电动机把电能转化为机械能，与发电机相反。", "category": "science"},
    {"prompt": "臭氧层主要能吸收太阳光中的哪种射线？", "options": [{"key":"A","text":"紫外线"},{"key":"B","text":"红外线"},{"key":"C","text":"无线电波"},{"key":"D","text":"微波"}], "correct_key": "A", "explanation": "臭氧层能吸收大部分对生物有害的紫外线。", "category": "science"},
    {"prompt": "下列哪种气体在空气中含量约占 0.04%，是光合作用原料？", "options": [{"key":"A","text":"氧气"},{"key":"B","text":"二氧化碳"},{"key":"C","text":"氮气"},{"key":"D","text":"氦气"}], "correct_key": "B", "explanation": "二氧化碳在空气中约占 0.04%，是光合作用的原料。", "category": "science"},
    {"prompt": "以下哪个天文现象是月球运行到太阳和地球之间造成的？", "options": [{"key":"A","text":"月食"},{"key":"B","text":"流星雨"},{"key":"C","text":"日食"},{"key":"D","text":"极光"}], "correct_key": "C", "explanation": "月球位于太阳和地球之间遮挡阳光时发生日食。", "category": "science"},
    {"prompt": "以下哪种物质属于混合物？", "options": [{"key":"A","text":"蒸馏水"},{"key":"B","text":"氧气"},{"key":"C","text":"黄金"},{"key":"D","text":"空气"}], "correct_key": "D", "explanation": "空气由多种气体混合而成，属于混合物。", "category": "science"},
    {"prompt": "下列哪种情况下物体的重力势能最大？", "options": [{"key":"A","text":"位置越高"},{"key":"B","text":"位置越低"},{"key":"C","text":"速度越快"},{"key":"D","text":"温度越高"}], "correct_key": "A", "explanation": "重力势能随高度增加而增大。", "category": "science"},
    {"prompt": "地球上的水循环主要靠什么提供能量？", "options": [{"key":"A","text":"月球"},{"key":"B","text":"太阳"},{"key":"C","text":"地热"},{"key":"D","text":"风"}], "correct_key": "B", "explanation": "太阳辐射驱动水的蒸发与循环。", "category": "science"},
    {"prompt": "下列哪位科学家因发现万有引力定律而闻名？", "options": [{"key":"A","text":"爱因斯坦"},{"key":"B","text":"特斯拉"},{"key":"C","text":"牛顿"},{"key":"D","text":"焦耳"}], "correct_key": "C", "explanation": "艾萨克·牛顿提出了万有引力定律。", "category": "science"},
    {"prompt": "以下哪种动物属于爬行动物？", "options": [{"key":"A","text":"青蛙"},{"key":"B","text":"企鹅"},{"key":"C","text":"蝙蝠"},{"key":"D","text":"蜥蜴"}], "correct_key": "D", "explanation": "蜥蜴是典型的爬行动物。", "category": "science"},
    {"prompt": "以下哪种简单几何体只有一个面？", "options": [{"key":"A","text":"球"},{"key":"B","text":"正方体"},{"key":"C","text":"圆柱"},{"key":"D","text":"圆锥"}], "correct_key": "A", "explanation": "球只有一个连续的曲面。", "category": "science"},
    {"prompt": "人体血液呈红色主要是因为含有什么？", "options": [{"key":"A","text":"叶绿素"},{"key":"B","text":"血红蛋白"},{"key":"C","text":"胆红素"},{"key":"D","text":"黑色素"}], "correct_key": "B", "explanation": "血红蛋白中含铁，与氧结合后使血液呈红色。", "category": "science"},
    {"prompt": "以下哪种现象是由于地球自转引起的？", "options": [{"key":"A","text":"四季更替"},{"key":"B","text":"月相变化"},{"key":"C","text":"昼夜交替"},{"key":"D","text":"潮汐"}], "correct_key": "C", "explanation": "地球自转导致昼夜交替。", "category": "science"},
    {"prompt": "下列哪种物质不导电？", "options": [{"key":"A","text":"铜"},{"key":"B","text":"铝"},{"key":"C","text":"石墨"},{"key":"D","text":"橡胶"}], "correct_key": "D", "explanation": "橡胶是绝缘体，通常不导电。", "category": "science"},
    {"prompt": "下列哪种维生素有助于夜间视力，缺乏会导致夜盲症？", "options": [{"key":"A","text":"维生素 A"},{"key":"B","text":"维生素 C"},{"key":"C","text":"维生素 D"},{"key":"D","text":"维生素 E"}], "correct_key": "A", "explanation": "维生素 A 与视觉有关，缺乏会引起夜盲症。", "category": "science"},
    {"prompt": "0.5 用分数表示是？", "options": [{"key":"A","text":"1/3"},{"key":"B","text":"1/2"},{"key":"C","text":"1/4"},{"key":"D","text":"2/3"}], "correct_key": "B", "explanation": "0.5 等于二分之一。", "category": "science"},
    {"prompt": "下列哪个星座常被用来在北半球寻找北极星？", "options": [{"key":"A","text":"猎户座"},{"key":"B","text":"天蝎座"},{"key":"C","text":"北斗七星（大熊座）"},{"key":"D","text":"仙女座"}], "correct_key": "C", "explanation": "利用北斗七星的斗口两星连线可找到北极星。", "category": "science"},
    {"prompt": "下列哪种物态变化需要吸收热量？", "options": [{"key":"A","text":"凝固"},{"key":"B","text":"液化"},{"key":"C","text":"凝华"},{"key":"D","text":"熔化"}], "correct_key": "D", "explanation": "熔化（固体变液体）需要吸收热量。", "category": "science"},
    {"prompt": "下列哪种细胞器被称为细胞的「能量工厂」？", "options": [{"key":"A","text":"线粒体"},{"key":"B","text":"细胞核"},{"key":"C","text":"核糖体"},{"key":"D","text":"高尔基体"}], "correct_key": "A", "explanation": "线粒体是细胞进行有氧呼吸、产生能量的主要场所。", "category": "science"},
    {"prompt": "下列哪种现象体现了惯性？", "options": [{"key":"A","text":"磁铁吸铁"},{"key":"B","text":"汽车急刹车时人向前倾"},{"key":"C","text":"灯泡发光"},{"key":"D","text":"水往低处流"}], "correct_key": "B", "explanation": "急刹车时人因惯性保持前进趋势而前倾。", "category": "science"},
    {"prompt": "以下哪个是人体循环系统的核心器官？", "options": [{"key":"A","text":"肺"},{"key":"B","text":"肝"},{"key":"C","text":"心脏"},{"key":"D","text":"肾"}], "correct_key": "C", "explanation": "心脏是推动血液循环的核心器官。", "category": "science"},
    {"prompt": "下列哪种金属最轻（密度最小）？", "options": [{"key":"A","text":"铁"},{"key":"B","text":"铅"},{"key":"C","text":"铜"},{"key":"D","text":"锂"}], "correct_key": "D", "explanation": "锂是密度最小的金属，能浮在水面上。", "category": "science"},
    {"prompt": "下列哪种波长最长？", "options": [{"key":"A","text":"无线电波"},{"key":"B","text":"可见光"},{"key":"C","text":"X 射线"},{"key":"D","text":"γ 射线"}], "correct_key": "A", "explanation": "在电磁波谱中，无线电波波长最长。", "category": "science"},
    {"prompt": "以下哪种气体常被填充在飞艇或气球中使其上升，且不易燃？", "options": [{"key":"A","text":"氢气"},{"key":"B","text":"氦气"},{"key":"C","text":"氧气"},{"key":"D","text":"二氧化碳"}], "correct_key": "B", "explanation": "氦气密度小且化学性质稳定不易燃，常用于气球。", "category": "science"},
    {"prompt": "下列哪个数学符号表示「大于」？", "options": [{"key":"A","text":"<"},{"key":"B","text":"="},{"key":"C","text":">"},{"key":"D","text":"≠"}], "correct_key": "C", "explanation": "符号「>」表示大于。", "category": "science"},
    {"prompt": "以下哪种自然现象与大气中水汽凝结无关？", "options": [{"key":"A","text":"云"},{"key":"B","text":"雾"},{"key":"C","text":"露"},{"key":"D","text":"地震"}], "correct_key": "D", "explanation": "云、雾、露都由水汽凝结形成，地震属于地质活动。", "category": "science"},
    {"prompt": "下列哪种成分是构成细胞膜的主要物质？", "options": [{"key":"A","text":"磷脂"},{"key":"B","text":"纤维素"},{"key":"C","text":"淀粉"},{"key":"D","text":"几丁质"}], "correct_key": "A", "explanation": "细胞膜以磷脂双分子层为基本骨架。", "category": "science"},
    {"prompt": "地球到太阳的平均距离约为多少？", "options": [{"key":"A","text":"约 3.8 万公里"},{"key":"B","text":"约 1.5 亿公里"},{"key":"C","text":"约 100 亿公里"},{"key":"D","text":"约 1 万公里"}], "correct_key": "B", "explanation": "日地平均距离约 1.5 亿公里，即 1 个天文单位。", "category": "science"},
]