diff --git a/test.py b/test.py
index 0730305..b2bde57 100644
--- a/test.py
+++ b/test.py
@@ -115,11 +115,12 @@ class Game:
         sky (Sky):                  天体情報
     """
 
-    clock:      Clock
-    frame:      int
-    redrawers:  list[Redrawer]
-    screen:     Surface
-    sky:        Sky
+    clock:              Clock
+    frame:              int
+    last_answered_at:   datetime
+    redrawers:          list[Redrawer]
+    screen:             Surface
+    sky:                Sky
 
     def __init__ (
             self,
@@ -383,6 +384,7 @@ class Balloon (GameObject):
     ) -> None:
         if self.frame >= self.length:
             self.enabled = False
+            self.game.last_answered_at = datetime.now ()
             return
         query = self.query
         if CommonModule.len_by_full (query) > 21: