语法这一术语有（）含义.
A、一种
B、两种
C、三种
D、四种
参考答案：C
________ a teacher, John thinks that his main duty is to help the students to become better learners. [ ]
A. As
B. By
C. About
在PID图的标题栏中不需要填写的内容有（）。
A、图名
B、图号
C、比例
D、设计阶段
