diff --git a/app/controllers/files_controller.rb b/app/controllers/files_controller.rb
index 791d145c2..a6eafe0f3 100644
--- a/app/controllers/files_controller.rb
+++ b/app/controllers/files_controller.rb
@@ -172,17 +172,17 @@ class FilesController < ApplicationController
       attachment_ids.each do |attachment_id|
         ori = Attachment.find_by_id(attachment_id)
         # 同一个资源可以多次发送到课堂
-        # @course.attachments.each do |att|
-        #   @exist = false
-        #   if att.id == ori.id || (!att.copy_from.nil? && !ori.copy_from.nil? && att.copy_from == ori.copy_from) || att.copy_from == ori.id || att.id == ori.copy_from
-        #     att.created_on = Time.now
-        #     att.save
-        #     @exist = true
-        #     break
-        #   end
-        # end
-        #
-        # next if @exist
+        @course.attachments.each do |att|
+          @exist = false
+          if att.id == ori.id || (!att.copy_from.nil? && !ori.copy_from.nil? && att.copy_from == ori.copy_from) || att.copy_from == ori.id || att.id == ori.copy_from
+            att.created_on = Time.now
+            att.save
+            @exist = true
+            break
+          end
+        end
+
+        next if @exist
         attach_copied_obj = ori.copy
         attach_copied_obj.container = @course
         attach_copied_obj.created_on = Time.now