在我们区进行的七年级期中检测题中,有这样一道来自课本的试题:“一个缺角三角形残片如图所示,不恢复这个缺角,请你作出AB边上的高所在的直线.你是怎样作的?请你说明理由.”该试题旨在考查学生利用所学的知识:“三角形的三条高所在的直线交于一点”来进行作图解决问题.所给的答案是这样的:作两残片边上三角形的高AE、BF交于点O;过点O作AB的垂线MN,直线MN就是所求作的直线. In our district seventh grade mid-term test questions, there is such a textbook from the test: “A missing triangle fragments shown in the figure, do not restore the missing corner, you make a high AB on the edge of the line. How do you do it? Please explain why. ”The question is designed to examine how students use the knowledge they have learned:“ The triangle's three straight lines intersect at a single point. ” This is the case: for the triangle edge of the two fragments of the high AE, BF to point O; O point over the AB for the vertical MN, the line is the straight line MN is seeking.