objective questions to reinforce C knowledge

采用B/S结构，实现完全的在线考试，支持单选、多选、判断、填空、简答等题型，支持题库的维护和管理，主观题自动判卷、客观题由老师判卷，可生成学生答卷-With B/S structure, to achieve complete online examinations, support radio, multiple choice, judgment, fill in the blank, short-answer questions, etc., to support the maintenan