技校《工程力学》课本劳动版第二版第四章第一节平面任意力系的平衡，是《工程力学》静力学部分的重点，也是难点，其方程又是整个静力平衡方程的总结，教学大纲要求学生必须掌握。而教材对此既无严密推理，又缺乏综合归纳，仅用几个可能性引出，显得既突然又模糊，给学生的理 Technical school “Engineering Mechanics” textbook version second edition labor force second chapter fourth section the balance of any force system is “engineering mechanics” static part of the focus, but also difficult, the equation is the summary of the entire static balance equation, Syllabus requires students to master. The textbook neither strict reasoning, but also a lack of comprehensive induction, only a few possibilities, it seems both sudden and fuzzy, to the students