题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-63836.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-35629.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-60714.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-20554.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-69243.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-92763.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-19589.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-77908.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-33527.png)
(1)若
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-62041.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-58440.png)
(2)求直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-99713.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-82768.png)
解析
试题分析:本题主要考查线线平行、线面平行、线线垂直、线面垂直、线面角、向量法等基础知识,考查学生的空间想象能力、逻辑推理能力、计算能力.第一问,取BC中点,由中位线及平行线间的传递性,得到
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-66686.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-47270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-32253.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-34230.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-62041.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-43272.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-58440.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-47091.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-99929.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-11098.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-82425.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-16998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-60714.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-39365.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-92061.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-63903.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-20525.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-89075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-22814.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-74361.png)
试题解析:『法一』(1)取
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-24705.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-73529.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-84915.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-83949.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-66686.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-47270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-32253.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-34230.png)
且平面
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-21666.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-77679.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-93539.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-89574.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-81221.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015250-21666.png)
且
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-62041.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-62041.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-43272.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-92763.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-19589.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-77908.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-27066.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-99713.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-51616.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-39662.png)
(2)连结
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-47091.png)
因为三棱柱
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-63836.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-99929.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-11098.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-82425.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-16998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-60714.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-20554.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-69243.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-26780.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015251-34384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-16998.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-96348.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-64050.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-63903.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-20525.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-20525.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-56638.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-20525.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
∴直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-20525.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-30579.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-97322.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015253-93729.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015253-30508.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015253-98421.png)
∴直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-82768.png)
『法二』(1)因为三棱柱
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-63836.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-99929.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015249-11098.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015246-35629.png)
∴以
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015253-76154.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015253-37506.png)
所在直线为
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015254-37786.png)
建立如图空间直角坐标系. 1分
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015254-68215.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015254-91410.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-30579.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
等腰三角形,所以
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015252-97322.png)
易得
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015254-48311.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015255-57291.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015255-14225.png)
所以有
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015255-22673.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015255-71996.png)
设平面
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015255-77754.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015256-97588.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015256-55945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015256-89421.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015256-75268.png)
(也可直接证明
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015257-49484.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015257-78996.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015257-56489.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015257-66551.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015258-30613.png)
若
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-62041.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015258-86152.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015258-83331.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015258-54998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015258-82500.png)
解得
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015259-47382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-99713.png)
(2)由(1)可知平面
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015256-75268.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015259-11636.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015259-13079.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015259-44704.png)
设直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015300-95365.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015300-33588.png)
则
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015300-43125.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015300-71520.png)
∴直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-13542.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015247-48137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015248-82768.png)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015226-89799.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015226-87464.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-19524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-25350.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-82313.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-64033.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-29714.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-69749.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015227-46035.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-90031.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-67664.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-18552.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-90031.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-60933.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-95529.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015229-36298.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015229-41567.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-95529.png)
(2)求折后直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015229-87485.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015228-95529.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015230-66846.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015208-79444.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015208-62315.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015208-30832.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015208-11808.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015209-92105.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015209-37763.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015209-44777.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015209-64289.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015210-42616.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015208-62315.png)
(2)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015210-74382.png)
(3)证明:在线段
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015210-95572.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015210-55214.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015211-85590.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015211-30675.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015211-47461.png)
DC//AB,DA=DC=2AB.
(1)若点E为棱PA上一点,且OE∥平面PBC,求
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015153-90159.png)
(2)求证:平面PBC^平面PDC.
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015154-15702.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015133-21755.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015133-79863.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-56957.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-64596.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-81007.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-83989.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-65958.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-99757.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015135-90884.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015135-59159.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015135-74329.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015136-53918.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015136-76413.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015136-98960.png)
(2)求直线
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015136-70185.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015136-79554.png)
(3)线段
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015134-99757.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015137-19208.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015136-79554.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015137-37134.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015137-52908.png)
不存在,说明理由.
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015114-27377.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015114-18333.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015115-39170.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015115-47188.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015115-64305.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015115-38548.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015115-41717.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015116-93533.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015116-82239.png)
(2)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191106/20191106015116-85257.png)
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- 1把下列句子翻译成现代汉语。(1)呜呼!其信然邪?其梦邪?其传之非其真邪? 译文:____________________
- 2听句子,选择与你所听到的句子内容相符的图画。每个句子读两遍。 A
- 3以下两题,任选其一,完成写作。 (1)仔细观察徐悲鸿的画作《逆风》,按要求作文。 要求:①领会画作的含意,以此生发联
- 4—Are your pencils on the desk? —No, _____. [ ]A. they ar
- 5温家宝总理曾在政府工作报告中庄严承诺:“我们所作的一切都是要让人民生活得更加幸福、更有尊严”。而今,这种承诺正在一步步地
- 6根据句意,用括号内所给单词的正确形式填空。1. Don"t read in the sun. It may _____
- 7(08孝感第二次统考)甲午中日战争后,中国的近代化内容出现了新的变化,开始由“政策创新”转向“体制创新。”导致这种转变的
- 8下列离子方程式书写正确的是A.铝粉投入到NaOH溶液中:2Al+2OH-=2AlO2-+H2↑B.AlCl3溶液中加入足
- 9_____, he suddenly found the shop he was looking for.A.When
- 10图中阴影部分表示世界和我国的工业区。读图判断第下列各题。小题1:有关三个工业区的叙述正确的是 ( )A.甲工业区是
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- 1某学习小组围绕“气体实验室制取”进行了研讨.请你参与完成下面的问题.(1)原理分析:图①和图②装置都能用于实验室制取氧气
- 2下列实验操作正确的是A.用溶液检验两瓶均为红棕色的气体:和蒸汽B.用托盘天平称取4.56克食盐C.苯酚粘到手上,应马上用
- 3已知一个空间几何体的三视图如图所示,根据图中标出的尺寸(单位:cm)可得这个几何体的体积是( )cm3。
- 4世界人口的增长存在着很大的地区差异。分析下表,关于X国和Y国的正确说法是[ ]A、X国可能在北美 B、Y国可能在
- 5—Shall we watch a ballet together? —That’s a good idea, __
- 62009年,在诺贝尔奖各奖项即将揭晓之际,诺贝尔基金会评出了诺贝尔奖百余年历史上 “最受尊崇的”三位获奖者。其中之一是1
- 7在显微镜下能看清写在载玻片上的“OP”两字是“__________”字,将载玻片往左移看到的物象却不是往左移,这个现象说
- 8已知,如图甲,在△ABC中,AE平分∠BAC(∠C>∠B),F为AE上一点,且FD⊥BC于D.(1)试说明:∠EFD=1
- 9家用节能灯上标有“220V 11W”字样.当该灯正常工作时亮度接近60W的白炽灯,则它正常工作时的实际电功率是( )A
- 10小明同学通过实验研究浸在液体中的物体表面受到液体的压力大小与什么因素有关.他把高为0.2米的实心圆柱体先后浸入A、B、C