diff --git a/assets/section_3.1_1686980736370_0.edn b/assets/section_3.1_1686980736370_0.edn
index c31769f..e12e713 100644
--- a/assets/section_3.1_1686980736370_0.edn
+++ b/assets/section_3.1_1686980736370_0.edn
@@ -94,16 +94,21 @@
                           :page 16},
                :content {:text "[:span]", :image 1686982484555},
                :properties {:color "yellow"}}
-              {:id #uuid "648d5204-8b2e-4072-b2bf-f86c6345a5e1",
+              {:id #uuid "648d5223-4e70-4b61-bb3c-89bad7b2d755",
                :page 22,
-               :position {:bounding {:x1 38,
-                                     :y1 122.25,
-                                     :x2 690,
-                                     :y2 461.25,
+               :position {:bounding {:x1 56.686195373535156,
+                                     :y1 207.82552337646484,
+                                     :x2 355.5143127441406,
+                                     :y2 231.99217987060547,
                                      :width 725.67,
                                      :height 544.252},
-                          :rects (),
+                          :rects ({:x1 56.686195373535156,
+                                   :y1 207.82552337646484,
+                                   :x2 355.5143127441406,
+                                   :y2 231.99217987060547,
+                                   :width 725.67,
+                                   :height 544.252}),
                           :page 22},
-               :content {:text "[:span]", :image 1686983172049},
-               :properties {:color "yellow"}}],
- :extra {:page 22}}
+               :content {:text "Find the joint d.f. of X and Y ."},
+               :properties {:color "blue"}}],
+ :extra {:page 27}}
diff --git a/assets/section_3.1_1686980736370_0/22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png b/logseq/.recycle/assets_section_3.1_1686980736370_0_22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png
similarity index 100%
rename from assets/section_3.1_1686980736370_0/22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png
rename to logseq/.recycle/assets_section_3.1_1686980736370_0_22_648d5204-8b2e-4072-b2bf-f86c6345a5e1_1686983172049.png
diff --git a/pages/hls__section_3.1_1686980736370_0.md b/pages/hls__section_3.1_1686980736370_0.md
index cf124ab..a7b7d25 100644
--- a/pages/hls__section_3.1_1686980736370_0.md
+++ b/pages/hls__section_3.1_1686980736370_0.md
@@ -57,10 +57,8 @@ file-path:: ../assets/section_3.1_1686980736370_0.pdf
   id:: 648d4f55-569b-404b-a473-6f155efb0dda
   hl-type:: area
   hl-stamp:: 1686982484555
-- [:span]
+- Find the joint d.f. of X and Y .
   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
+  hl-color:: blue
+  id:: 648d5223-4e70-4b61-bb3c-89bad7b2d755
\ No newline at end of file
diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md
index 2770262..b375d58 100644
--- a/pages/总复习2023t1.md
+++ b/pages/总复习2023t1.md
@@ -2885,8 +2885,9 @@
 							- Marginal p.f. : ((648d4f45-89ee-420b-9b93-13076e232dff))
 							  collapsed:: true
 								- ((648d4f55-569b-404b-a473-6f155efb0dda))
-							- d.f. of random vector
-								-
+							- d.f. of random vector, example:
+								- ((648d5223-4e70-4b61-bb3c-89bad7b2d755))
+							-
 			- LATER 学积分
 			  :LOGBOOK:
 			  CLOCK: [2023-06-03 Sat 17:05:07]--[2023-06-03 Sat 17:05:08] =>  00:00:01