立体几何中点的定位问题是一个重要题型,也是高考命题的热点.解这类题不仅要求考生空间想象力强,还必须具有扎实的基础知识及灵活应变的能力.而考生在此类问题面前往往不知如何入手,常常在图形和条件面前理 The positioning of the mid-point of the geometric geometry is an important problem, but also the focus of the college entrance examination proposition. Solutions such questions not only require the candidates space imagination, but also must have a solid foundation of knowledge and ability to respond flexibly. Often I do not know how to start, often in the face of graphics and conditions