diff --git a/db/migrate/20191223113621_modify_task_pass_for_challenges.rb b/db/migrate/20191223113621_modify_task_pass_for_challenges.rb
new file mode 100644
index 000000000..dbbbafced
--- /dev/null
+++ b/db/migrate/20191223113621_modify_task_pass_for_challenges.rb
@@ -0,0 +1,8 @@
+class ModifyTaskPassForChallenges < ActiveRecord::Migration[5.2]
+  def change
+    Challenge.find_each do |challenge|
+      task_pass = challenge.task_pass.gsub("", "").gsub("rac", '\frac')
+      challenge.update_attribute(:task_pass, task_pass)
+    end
+  end
+end
diff --git a/lib/tasks/excellent_course_exercise.rake b/lib/tasks/excellent_course_exercise.rake
index e05a813f4..a8f860c2d 100644
--- a/lib/tasks/excellent_course_exercise.rake
+++ b/lib/tasks/excellent_course_exercise.rake
@@ -14,19 +14,19 @@ namespace :excellent_course_exercise do
     course = Course.find_by(id: course_id)
 
     course.exercises.each_with_index do |exercise, index|
-      # if exercise.exercise_users.where(commit_status: 1).count == 0
+      if exercise.exercise_users.where(commit_status: 1).count == 0
         # 第一个试卷的参与人数和通过人数都是传的数据，后续的随机
         if index == 0
           members = course.students.order("id asc").limit(participant_count)
           update_exercise_user(exercise, members, pass_count)
         else
-          new_participant_count = rand((participant_count - 423)..participant_count)
-          new_pass_count = rand((new_participant_count - 113)..new_participant_count)
+          new_participant_count = rand((participant_count - 20)..participant_count)
+          new_pass_count = rand((new_participant_count - 30)..new_participant_count)
 
           members = course.students.order("id asc").limit(new_participant_count)
           update_exercise_user(exercise, members, new_pass_count)
         end
-      # end
+      end
     end
   end
 
@@ -36,14 +36,15 @@ namespace :excellent_course_exercise do
     # index < pass_count 之前的学生都是通关的，之后的未通过
     members.each_with_index do |member, index|
       exercise_user = exercise.exercise_users.where(user_id: member.user_id).take
-      if exercise_question_ids.length == 20
+      question_length = exercise_question_ids.length
+      if question_length == 20
         rand_num = index < pass_count - 1 ? rand(15..20) : rand(1..10)
-      elsif exercise_question_ids.length == 17
+      elsif question_length == 17
         rand_num = index < pass_count - 1 ? rand(12..17) : rand(1..9)
-      elsif exercise_question_ids.length == 39
+      elsif question_length == 39
         rand_num = index < pass_count - 1 ? rand(30..39) : rand(1..18)
       else
-        rand_num = exercise_question_ids.length
+        rand_num = index < pass_count - 1 ? rand((question_length-3)..question_length) : rand(1..(question_length-8))
       end
 
       if exercise_user && exercise_user.commit_status == 0
diff --git a/lib/tasks/migrate_course_student.rake b/lib/tasks/migrate_course_student.rake
new file mode 100644
index 000000000..913cb2562
--- /dev/null
+++ b/lib/tasks/migrate_course_student.rake
@@ -0,0 +1,32 @@
+# 执行示例  RAILS_ENV=production bundle exec rake migrate_course_student:student args=3835,2526,21950,1000
+# args 第一个课程 course_id，第二个参数是学校school_id，第三个参数是部门id，第四个参数是迁移数量
+#
+
+desc "同步学校的学生"
+namespace :migrate_course_student do
+  if ENV['args']
+    course_id = ENV['args'].split(",")[0] # 对应课堂的id
+    school_id = ENV['args'].split(",")[1] # 对应学校id
+    department_id = ENV['args'].split(",")[2] # 对应部门id
+    limit = ENV['args'].split(",")[3] # 限制导入的数量
+  end
+
+  task :student => :environment do
+    course = Course.find course_id
+    users = User.joins(:user_extension).where(user_extensions: {school_id: school_id, department_id: department_id, identity: 1}).limit(limit)
+    user_ids = []
+
+    users.each do |user|
+      if user.student_id.present? && !course.students.exists?(user_id: user.id)
+        begin
+          CourseMember.create!(course_id: course_id, user_id: user.id, role: 4)
+          user_ids << user.id
+        rescue Exception => e
+          Rails.logger(e.message)
+        end
+      end
+    end
+    CourseAddStudentCreateWorksJob.perform_later(course_id, user_ids)
+
+  end
+end
\ No newline at end of file