垂直关系是空间元素间的重要位置关系，是高中数学教学的重点，也是历年高考考查的热点．在各种垂直关系中最关键的是两条直线的垂直关系（以下简称“线线垂直”），要证“线面垂直”和“面面垂直”常化为证“线线垂直”，由“线线垂直”常可得“线面垂直”和“面面垂直”... The vertical relationship is an important positional relationship among spatial elements. It is the focus of high school mathematics teaching, and it is also a hot spot of the college entrance examination. The most critical of the various vertical relationships is the vertical relationship between the two straight lines (hereinafter referred to as “line vertical”). It is necessary to prove that the “vertical line surface” and “vertical surface” are normalized to permit “vertical line”. “Vertical lines” often have “line vertical” and “vertical surface”...