diff --git a/assets/section_3.2_1686984934976_0.edn b/assets/section_3.2_1686984934976_0.edn
new file mode 100644
index 0000000..ab9a38b
--- /dev/null
+++ b/assets/section_3.2_1686984934976_0.edn
@@ -0,0 +1 @@
+{:highlights [], :extra {:page 1}}
diff --git a/assets/section_3.2_1686984934976_0.pdf b/assets/section_3.2_1686984934976_0.pdf
new file mode 100644
index 0000000..49ecbb5
Binary files /dev/null and b/assets/section_3.2_1686984934976_0.pdf differ
diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md
index 27a613f..0f64e02 100644
--- a/pages/总复习2023t1.md
+++ b/pages/总复习2023t1.md
@@ -2887,14 +2887,20 @@
 							  collapsed:: true
 								- ((648d4f55-569b-404b-a473-6f155efb0dda))
 							- d.f. of random vector, example:
+							  collapsed:: true
 								- ((648d5223-4e70-4b61-bb3c-89bad7b2d755))
 							-
 						- Continuous random vector
+						  collapsed:: true
 							- Definition of jpdf:
+							  collapsed:: true
 								- ((648d525e-f08f-4838-9103-0218fb369579))
 							- Calculating p.d.f. from d.f
+							  collapsed:: true
 								- ((648d5392-d808-41be-82da-e23934db4f9f))
-							-
+							- LATER bi-variate normal distribution
+					- Independence of random variables ![section 3.2.pdf](../assets/section_3.2_1686984934976_0.pdf)
+						-
 			- LATER 学积分
 			  :LOGBOOK:
 			  CLOCK: [2023-06-03 Sat 17:05:07]--[2023-06-03 Sat 17:05:08] =>  00:00:01