json.extract! exercise, :id, :exercise_name,:is_public,:created_at,:exercise_status
json.lock_status lock_icon
json.publish_time exercise_publish_time  # 试卷的发布时间
json.end_time exercise_end_time   # 试卷的截止时间
json.exercise_answer exercise_answer  # 已提交试卷的用户
json.exercise_unanswer exercise_unanswer  # 已查看试卷/开始答题，但是未提交试卷的用户
json.current_status current_status  #答题的状态

