a complicated social phenomenon
例：课程、教师、学生作为数学教育的核心要素，反映到数学教育改革中，既是一项复杂的社会现象，又是一项复杂的系统工程。
The key element which course, teacher, student educate as mathematics, reflectin the educational reform of mathematics, it is a complicated social phenomenon, it is a complicated system engineering.
