diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md
index ae135a5..5f2f619 100644
--- a/pages/总复习2023t1.md
+++ b/pages/总复习2023t1.md
@@ -959,6 +959,9 @@
 					- LATER SQL join
 			- LATER Block 2
 				- LATER EER
+					- Most useful additional concept of EER model:
+					  specialization/generalization.
+						- Superclass :->
 				- LATER designing ER diagram
 			- DONE Block 3
 			  collapsed:: true