diff --git a/trailminator/dst.py b/trailminator/dst.py
index 8bbf494..40fbef1 100644
--- a/trailminator/dst.py
+++ b/trailminator/dst.py
@@ -1,9 +1,24 @@
 class Dst:
     def __init__(self):
         self.messages = []
+        self.checklist = {
+            "from": None,
+            "to": None,
+            "time": None,
+            "passangerCount": None,
+            "discountedCount": None,
+            "seatType": None,
+            "wagonType": None
+        }
+        self.history = []
     
     def store(self, message):
         self.messages.append(message)
 
     def get_messages(self):
         return self.messages
+
+    def get_next_question(self):
+        for key, value in self.checklist.items():
+            if value == None:
+                return key
diff --git a/trailminator/nlu.py b/trailminator/nlu.py
index 328e020..400b5b9 100644
--- a/trailminator/nlu.py
+++ b/trailminator/nlu.py
@@ -39,6 +39,8 @@ class Nlu:
                     if t in v['parameters']:
                         param.append(t)
 
+    # TODO: Refactor
+
 
         return (act, param)
 
diff --git a/trailminator/trailminator.py b/trailminator/trailminator.py
index 5cc2adc..8f9011a 100644
--- a/trailminator/trailminator.py
+++ b/trailminator/trailminator.py
@@ -10,3 +10,6 @@ if __name__ == "__main__":
     nlg_params = dp.Dp(*dp_params).identify()
     # print(nlg_params)
     print(f"{msg}\n{nlg.Nlg(nlg_params).response()}")
+
+    d = dst.Dst()
+    print(d.get_next_question())