名校
解题方法
1 . 如图, 四棱锥
中,
是菱形,
,
,
分别为
和
的中点.
平面
;
(2)在AD上是否存在一点M,使得平面PMB⊥平面PAD?若存在请证明,若不存在请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4293e5984a5779e53b11c7370364d13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06222ee533c2484ab25321a6abbf98cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)在AD上是否存在一点M,使得平面PMB⊥平面PAD?若存在请证明,若不存在请说明理由.
您最近一年使用:0次
2 . “让式子丢掉次数”—伯努利不等式(Bernoulli’sInequality),又称贝努利不等式,是高等数学分析不等式中最常见的一种不等式,由瑞士数学家雅各布.伯努利提出,是最早使用“积分”和“极坐标”的数学家之一.贝努利不等式表述为:对实数
,在
时,有不等式
成立;在
时,有不等式
成立.
(1)证明:当
,
时,不等式
成立,并指明取等号的条件;
(2)已知
,…,
(
)是大于
的实数(全部同号),证明:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30cdfc52dbd70827de9e15fffe39c321.png)
(3)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bc98a4d9ae0580aa2c1152ffb770d4d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c4fb8df3614557f13bdc68378437e90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3d4045366a437d4003259050718e244.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f75f0daa973c8fc183b7d21bafd7e8cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c78998ba5f2665a1753c3fa84751716.png)
(1)证明:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65a40142c84be68ee2918c3a8303388c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bc98a4d9ae0580aa2c1152ffb770d4d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5026dc5ead3b5adf0e5f4b3e7c4eca1d.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a1cc5cfec94bc5686b41b043acdc8ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3282e5fde4ae53fcb1bb072a685304c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a37a59558292ad6b3d0978bfd7484990.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acbc6a613224461ade69362d46550474.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30cdfc52dbd70827de9e15fffe39c321.png)
(3)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6b29215b2a741c01efc27199e6c6925.png)
您最近一年使用:0次
2024-05-30更新
|
288次组卷
|
3卷引用:2024年海南省海口实验中学高一学科竞赛选拔性考试(自主招生)数学试题
3 . 已知椭圆
经过点
,且焦距为
.
(1)求椭圆
的方程;
(2)设椭圆
的左、右顶点分别为
、
,点
为椭圆
上异于
、
的动点,设
交直线
于点
,连接
交椭圆
于点
,直线
的斜率分别为
.
①求证:
为定值;
②证明:直线
经过
轴上的定点,并求出该定点的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad523e69a1bf925e73a22900b9855df2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7160d93f92089ef36f3dab809d3114b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38387ba1cadfd3dfc4dea4ca9f613cea.png)
(1)求椭圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)设椭圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f23d29646155e27b172ecdf263e2d702.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b1ec05e3cec27677ded7b4aecaa62d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5671fb25040a712a49e8c8148d67d300.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/706325cc86b99fe9955185aa92a8fcab.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d53a52aebd885294e323ee90c9b5382.png)
②证明:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
您最近一年使用:0次
4 . 如图,在三棱柱ABC-A1B1C1中,AA1C1C是边长为4的正方形.平面ABC⊥平面AA1C1C,AB=3,BC=5.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/13/4ca3cfb7-fea0-4c1f-b33e-a301806e022c.png?resizew=140)
(Ⅰ)求证:AA1⊥平面ABC;
(Ⅱ)求二面角A1-BC1-B1的余弦值;
(Ⅲ)证明:在线段BC1存在点D,使得AD⊥A1B,并求
的值.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/13/4ca3cfb7-fea0-4c1f-b33e-a301806e022c.png?resizew=140)
(Ⅰ)求证:AA1⊥平面ABC;
(Ⅱ)求二面角A1-BC1-B1的余弦值;
(Ⅲ)证明:在线段BC1存在点D,使得AD⊥A1B,并求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c04c68f1ef1e37534b5bbc7a1f592ef7.png)
您最近一年使用:0次
2016-12-02更新
|
4629次组卷
|
30卷引用:海南热带海洋学院附属中学2021届高三11月第二次月考数学试题
海南热带海洋学院附属中学2021届高三11月第二次月考数学试题2013年全国普通高等学校招生统一考试理科数学(北京卷)(已下线)2014届上海交大附中高三数学理总复习二空间向量与立体几何练习卷2016-2017学年湖北省重点高中联考协作体高二下学期期中考试数学(理)试卷湖北省宜昌市葛洲坝中学2018届高三9月月考数学(理)试题【全国百强校】江苏省泰州中学2017-2018学年高二6月月考数学(理)试题【全国百强校】宁夏银川一中2019届高三第四次月考数学(理)试题专题11.8 空间向量与立体几何(练)-江苏版《2020年高考一轮复习讲练测》湖南省长沙市长郡中学2017-2018学年高二下学期入学考试数学(理)试题人教A版(2019) 选择性必修第一册 过关斩将 第一章 空间向量与立体几何 专题强化练3 立体几何中的存在性与探究性问题福建省连城县第一中学2020-2021学年高二上学期第一次月考数学试题江西省景德镇一中2020-2021学年高二(2班)上学期期中考试数学试题(已下线)第一章 空间向量与立体几何单元检测(知识达标卷)-【一堂好课】2021-2022学年高二数学上学期同步精品课堂(人教A版2019选择性必修第一册)河北省涞水波峰中学2020-2021学年高二上学期期末数学试题(已下线)专题03 空间向量与立体几何-立体几何中的存在性与探究性问题-2021-2022学年高二数学同步练习和分类专题教案(人教A版2019选择性必修第一册)(已下线)专练9 专题强化练3-立体几何中的存在性与探究性问题-2021-2022学年高二数学上册同步课后专练(人版A版选择性必修第一册)(已下线)期中考试重难点专题强化训练(1)——向量的综合运用-2021-2022学年高二数学单元卷模拟(易中难)(2019人教A版选择性必修第一册+第二册)江西省靖安中学2021-2022学年高二上学期第一次月考数学(理)试题苏教版(2019) 选修第二册 名师精选 第六章 空间向量与立体几何云南省弥勒市第一中学2021-2022学年高二上学期第三次月考数学试题安徽省合肥市第八中学2021-2022学年高二下学期平行班开学考理科数学试题河南省濮阳市范县第一中学2021-2022学年高二上学期第二次月考检测数学试题河南省鹤壁市浚县浚县第一中学2021-2022学年高一下学期7月月考数学试题2023版 北师大版(2019) 选修第一册 名师精选卷 第三章 空间向量与立体几何北京市丰台区第十二中学2021-2022学年高二上学期期中数学试题重庆市忠县乌杨中学校2021-2022学年高二上学期期中数学试题云南省曲靖市罗平县第二中学2021-2022学年高二上学期第二次月考数学试题福建省福州市福州中加学校2023-2024学年高二上学期期中数学试题(已下线)第五章 破解立体几何开放探究问题 专题一 立体几何存在性问题 微点1 立体几何存在性问题的解法(一)【基础版】(已下线)【一题多解】存在与否 向量探索
名校
解题方法
5 . 如图,已知四棱锥
中,底面
是平行四边形,
为侧棱
的中点.![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a6e2867f32d3f1c3cd36cd3a11a8580.png)
平面
;
(2)若
为侧棱
的中点,求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c2bc5e50b8dfa02601c70822252854a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a6e2867f32d3f1c3cd36cd3a11a8580.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/466fabcaac59132fea648ff35342ec9d.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d923a338dd2d2e29336b42574d38448.png)
您最近一年使用:0次
解题方法
6 . 如图,正方体
的棱长为3,点
在棱
上,点
在棱
上,
在棱
上,且
,
是棱
上一点.
,
,
,
四点共面;
(2)若平面
平面
,求证:
为
的中点.
(3)求平面
与平面
所成二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22d8fd9dbd9c0967145625b394f8182f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6795cae2df43a722e1355e9562d93c09.png)
(2)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e5ae0b183a311481b4c833959b068cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6069dc466eec75bbeb3d5c9b51cb3a70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
(3)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ef5ea43614d815c3abb27a42dfb101b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
您最近一年使用:0次
7日内更新
|
131次组卷
|
2卷引用:海南省2020-2021学年高二下学期期末考试数学试题
名校
7 . 在
中,角
、
、
所对的边分别为
、
、
,且满足:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6947e5cd4568c85eea02f5b3730b22c9.png)
(1)求角的A大小;
(2)若
,
,
,
分别为
,
上的两点
,
,
,
相交于点![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(i)求
的值;
(ii)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6947e5cd4568c85eea02f5b3730b22c9.png)
(1)求角的A大小;
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a7b5adfcac0f46a4cd19da4ebb4a2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73497849a8350d927c59a45604962408.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea6ef3d1c748bb068d95efd3917b9b29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7785afeeaf274892253d04b4f693b367.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(i)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2f87d0222dfe905d4f4b8108cddf2d8.png)
(ii)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e4ece75fe9b8555909be5a00d2b7af0.png)
您最近一年使用:0次
解题方法
8 . 已知函数
,等差数列
的前
项和为
,记
.
(1)求证:
的图象关于点
中心对称;
(2)若
,
,
是某三角形的三个内角,求
的取值范围;
(3)若
,求证:
.反之是否成立?并请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47665ff46fcf594d4151c3a89707257f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7830b11dc2634eb661673a04287ddc6.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ebbb2eab12b76127cc87304c212cdd6.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c1ccc6c74b8754e9bcbb3f39a11b6f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/155c5f3a5c55e0c95191c5a893f63062.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ca95ba448d33b5e82aa1a3591dc0adf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4615a158e82ab5ff2c3a84f13d1ccda.png)
您最近一年使用:0次
9 . 已知函数
,且
的图象在
处的切线斜率为2.
(1)求m;
(2)求
的单调区间;
(3)若
有两个不等的实根
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f02ec33f2caccc63110feeef0ab275e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ec25b105130d71d3d529524671b6218.png)
(1)求m;
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b70f5b3ed05b816949d8811d5956ae0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ce7ae90d808f05e86ea063238e4b2f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/26d4f5a04663e6ea4d0f183d27a6ba59.png)
您最近一年使用:0次
名校
解题方法
10 . 如图,正方体
的棱长为2,E为
的中点,点M在
上.
平面
.
的中点;
(2)求直线EM与平面MCD所成角的大小,及点E到平面MCD的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe734023d4e70010a6b2cc3267cb86e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd0285afe567ca0b32f0ccafc30167cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82b724168afaee2ecddf97257180be18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe734023d4e70010a6b2cc3267cb86e.png)
(2)求直线EM与平面MCD所成角的大小,及点E到平面MCD的距离.
您最近一年使用:0次
2024-06-09更新
|
215次组卷
|
2卷引用:2024届海南省省直辖县级行政单位琼海市高考模拟预测数学试题