diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md
index 5f2f619..d15e828 100644
--- a/pages/总复习2023t1.md
+++ b/pages/总复习2023t1.md
@@ -961,7 +961,16 @@
 				- LATER EER
 					- Most useful additional concept of EER model:
 					  specialization/generalization.
-						- Superclass :->
+						- Superclass :-> An entity type that includes one or more distinct
+						  subgroupings of its occurrences.
+							- Superclass/subclass relationship is one-to-one
+							  (1:1).
+							- Superclass may contain overlapping or distinct
+							  subclasses.
+							  • Not all members of a superclass need be a
+							  member of a subclass.
+						- Subclass :-> A distinct subgrouping of occurrences of an entity
+						  type.
 				- LATER designing ER diagram
 			- DONE Block 3
 			  collapsed:: true