diff --git a/app/services/duplicate_course_service.rb b/app/services/duplicate_course_service.rb
index 21ed0e109..299f9a45a 100644
--- a/app/services/duplicate_course_service.rb
+++ b/app/services/duplicate_course_service.rb
@@ -113,7 +113,7 @@ class DuplicateCourseService < ApplicationService
           )
         end
 
-        origin_question.exercise_shixun_challenges.find_each do |sc, index|
+        origin_question.exercise_shixun_challenges.each_with_index do |sc, index|
           question.exercise_shixun_challenges.create!({position: index+1, challenge_id: sc.challenge_id,
                                                             shixun_id: sc.shixun_id, question_score: sc.question_score})
         end