工程制图课程重点学习的内容是 the key points of engineering drawing are（）。
A: 工具和标准介绍 drawing tool and standards
B: 三视图的相关知识 relevant knowledge of the three views.
C: 剖视图与断面图 seciton views and section
D: 专业图 professional drawings
A: 工具和标准介绍 drawing tool and standards
B: 三视图的相关知识 relevant knowledge of the three views.
C: 剖视图与断面图 seciton views and section
D: 专业图 professional drawings
