diff --git a/assets/section_3.1_1686980736370_0.edn b/assets/section_3.1_1686980736370_0.edn
index f0b6c15..c31769f 100644
--- a/assets/section_3.1_1686980736370_0.edn
+++ b/assets/section_3.1_1686980736370_0.edn
@@ -93,5 +93,17 @@
                           :rects (),
                           :page 16},
                :content {:text "[:span]", :image 1686982484555},
+               :properties {:color "yellow"}}
+              {:id #uuid "648d5204-8b2e-4072-b2bf-f86c6345a5e1",
+               :page 22,
+               :position {:bounding {:x1 38,
+                                     :y1 122.25,
+                                     :x2 690,
+                                     :y2 461.25,
+                                     :width 725.67,
+                                     :height 544.252},
+                          :rects (),
+                          :page 22},
+               :content {:text "[:span]", :image 1686983172049},
                :properties {:color "yellow"}}],
- :extra {:page 24}}
+ :extra {:page 22}}
diff --git a/assets/section_3.1_1686980736370_0/22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png b/assets/section_3.1_1686980736370_0/22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png
new file mode 100644
index 0000000..fa85c42
Binary files /dev/null and b/assets/section_3.1_1686980736370_0/22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png differ
diff --git a/pages/hls__section_3.1_1686980736370_0.md b/pages/hls__section_3.1_1686980736370_0.md
index 13cfffa..cf124ab 100644
--- a/pages/hls__section_3.1_1686980736370_0.md
+++ b/pages/hls__section_3.1_1686980736370_0.md
@@ -56,4 +56,11 @@ file-path:: ../assets/section_3.1_1686980736370_0.pdf
   hl-color:: yellow
   id:: 648d4f55-569b-404b-a473-6f155efb0dda
   hl-type:: area
-  hl-stamp:: 1686982484555
\ No newline at end of file
+  hl-stamp:: 1686982484555
+- [:span]
+  ls-type:: annotation
+  hl-page:: 22
+  hl-color:: yellow
+  id:: 648d5204-8b2e-4072-b2bf-f86c6345a5e1
+  hl-type:: area
+  hl-stamp:: 1686983172049
\ No newline at end of file
diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md
index 092c20e..2770262 100644
--- a/pages/总复习2023t1.md
+++ b/pages/总复习2023t1.md
@@ -2866,6 +2866,7 @@
 				  :END:
 					- Random vectors ![section 3.1.pdf](../assets/section_3.1_1686980736370_0.pdf)
 						- Random Vectors and joint distributions
+						  collapsed:: true
 							- Definition:
 							  collapsed:: true
 								- ((648d4a20-af7c-42d5-addc-b2909e3d9fa0))
@@ -2882,8 +2883,10 @@
 						- Discrete random vectors
 							- JPF : ((648d4f01-6942-43ea-b5a1-159b99d49d7a))
 							- Marginal p.f. : ((648d4f45-89ee-420b-9b93-13076e232dff))
-							- ((648d4f55-569b-404b-a473-6f155efb0dda))
-							-
+							  collapsed:: true
+								- ((648d4f55-569b-404b-a473-6f155efb0dda))
+							- d.f. of random vector
+								-
 			- LATER 学积分
 			  :LOGBOOK:
 			  CLOCK: [2023-06-03 Sat 17:05:07]--[2023-06-03 Sat 17:05:08] =>  00:00:01