diff --git a/app/helpers/exercise_helper.rb b/app/helpers/exercise_helper.rb
index a0e76cbdb..2c92ffad7 100644
--- a/app/helpers/exercise_helper.rb
+++ b/app/helpers/exercise_helper.rb
@@ -3,12 +3,11 @@ module ExerciseHelper
 
   # 单选
   def sigle_selection_standard_answer(params)
-    size = params.ord - 64
-    # 输入的为小写字母答案
+    size = params.ord - 96
     if size > 0
       answer = params.ord - 96
     else
-      answer = params.ord
+      answer = params.ord - 64
     end
   end