Why not stay at home the road is so slippery after the heavy snow? A. since that B. now that C. then that D. after that
让一价氢离子、一价氦离子和二价氦离子的混合物经过同一加速电场由静止开始加速,然后在同一偏转电场里偏转,(忽略离子重力影响)则它们会分
(北京市朝阳区)在下列日常生产和生活的实例中,属于减小压强的是 ( ) A.喝饮料用的吸管一端削成斜口 B.铁钉的尖端要做得细而尖
Emily was a very big fan of animals when she was a child. As a result, all she ever heard about growing up was Emily, you should be a 36 _. You're going to be great in that field. That's what you
化学与生产生活密切相关,下列物质的用途及解释均正确的是 选项用途解释 A可用FeCl3溶液刻蚀铜制电路板Fe3+的氧化性强于Cu2+ B碳与石英反应可冶炼粗
某学生为了测量一物体的质量,找到一个力电转换器,该转换器的输出电压正比于受压面的压力(比例系数为k),如图所示。测量时先调节输入端的电压
(本题满分12分) 在平面直角坐标系中,已知A1(-3,0),A2(3,0),P(x,y),M(,0),若实数λ使向量,λ,满足λ2·()2=·。 (1)求点P的轨迹方
(2009年上海卷理)(本题满分14分) 如图,在直三棱柱中,, ,求二面角的大小。