diff --git a/app/controllers/poll_bank_questions_controller.rb b/app/controllers/poll_bank_questions_controller.rb
index 19111f4ca..71f302115 100644
--- a/app/controllers/poll_bank_questions_controller.rb
+++ b/app/controllers/poll_bank_questions_controller.rb
@@ -127,7 +127,7 @@ class PollBankQuestionsController < ApplicationController
   end
 
   def poll_questions_params
-    params.require(:poll_question).permit(:question_title,:question_type,:is_necessary,:question_number,:max_choices,:min_choices)
+    params.permit(:question_title,:question_type,:is_necessary,:question_number,:max_choices,:min_choices)
   end
 
   def validates_params
diff --git a/app/models/exercise_bank_question.rb b/app/models/exercise_bank_question.rb
index 14b166333..fdd343f5a 100644
--- a/app/models/exercise_bank_question.rb
+++ b/app/models/exercise_bank_question.rb
@@ -1,6 +1,6 @@
 class ExerciseBankQuestion < ApplicationRecord
   belongs_to :exercise_bank
-  belongs_to :shixun
+  belongs_to :shixun, optional: true
   has_many :exercise_bank_shixun_challenges,:dependent => :destroy
   has_many :exercise_bank_choices, :dependent => :destroy
   has_many :exercise_bank_standard_answers, :dependent => :destroy