diff --git a/frontend/pages/question.json b/frontend/pages/question.json
index 33f943f..2704c96 100644
--- a/frontend/pages/question.json
+++ b/frontend/pages/question.json
@@ -209,7 +209,7 @@
           {
             "name": "knack",
             "label": "窍门",
-            "hiddenOn": "this.media_content == 'None' || this.media_content.length == 0"
+            "hiddenOn": "this.knack == 'None' || this.knack.length == 0"
           },
           {
             "name": "concise_explain",