diff --git a/docs/chapter_computational_complexity/performance_evaluation.md b/docs/chapter_computational_complexity/performance_evaluation.md
index 45031b2f..dc1806e7 100644
--- a/docs/chapter_computational_complexity/performance_evaluation.md
+++ b/docs/chapter_computational_complexity/performance_evaluation.md
@@ -16,7 +16,7 @@ comments: true
 - **时间效率** ，即算法的运行速度的快慢。
 - **空间效率** ，即算法占用的内存空间大小。
 
-数据结构与算法追求 “运行得快、内存占用少” ，而如何去评价算法效率则是非常重要的问题。
+数据结构与算法追求 “运行得快、内存占用少” ，而如何去评价算法效率则是非常重要的问题，因为只有知道如何评价算法，才能去做算法之间的对比分析，以及优化算法设计。
 
 ## 效率评估方法
 
diff --git a/docs/chapter_preface/installation.md b/docs/chapter_preface/installation.md
index 4574379d..42041255 100644
--- a/docs/chapter_preface/installation.md
+++ b/docs/chapter_preface/installation.md
@@ -40,32 +40,3 @@ comments: true
 
 1. 下载并安装 [.Net 6.0](https://dotnet.microsoft.com/en-us/download) ；
 2. 在 VSCode 的插件市场中搜索 `c#` ，安装 c# 。
-
-
-
-
-Section | C++ | Python | Go | JavaScript #120 | TypeScript #121 | C | C# | Rust #112
--- | -- | -- | -- | -- | -- | -- | -- | --
-Performance Evaluation | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @krahets </li></ul> |   |   |   |   |   |  
-Time Complexity | <ul><li>[x] <ul><li>[x] @krahets </li></ul> </li></ul> | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @msk397 </li></ul> @Cathay-Chen |   |   |   |   |  
-Space Complexity | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @krahets </li></ul> |   |   |   |   |   |  
-Space Time Tradeoff | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @krahets </li></ul> | @Reanon | @gyt95 | @gyt95 |   |   |  
-Array | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @krahets </li></ul> |   | @IsChristina | @justin-tse |   | @mingXta |  
-LinkedList | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @krahets </li></ul> |   | @justin-tse @IsChristina | @justin-tse |   | @mingXta |  
-List | <ul><li>[x] @krahets </li></ul> | <ul><li>[x] @krahets </li></ul> |   | @justin-tse @IsChristina | @justin-tse |   |   |  
-Stack | @qualifier1024 | @pengchzn | @Reanon | @S-N-O-R-L-A-X (brewing) | @S-N-O-R-L-A-X (brewing) |   |   |  
-Queue | @qualifier1024 | @pengchzn | @Reanon | @S-N-O-R-L-A-X (brewing) | @S-N-O-R-L-A-X (brewing) |   |   |  
-Deque | <ul><li>[x] @krahets </li></ul> | @pengchzn | @Reanon |   |   |   |   |  
-Hashing | <ul><li>[x] @msk397 </li></ul> | <ul><li>[x] @msk397 </li></ul> | <ul><li>[x] @msk397 </li></ul> |   |   |   |  
-Hash Collision |   |   |   |   |   |   |   |  
-Binary Tree | <ul><li>[x] @krahets </li></ul> |   | @Reanon | @IsChristina | @justin-tse |   |   |  
-Binary Tree Types | <ul><li>[x] @krahets </li></ul> |   | @Reanon | @IsChristina | @justin-tse |   |   |  
-Binary Search Tree | <ul><li>[x] @krahets </li></ul> |   | @Reanon | @IsChristina | @justin-tse |   |   |  
-AVL Tree |   |   |   |   |   |   |   |  
-Linear Search | <ul><li>[x] @krahets </li></ul> | @Boy-timi |   |   |   |   |   |  
-Binary Search | <ul><li>[x] @krahets </li></ul> | @Boy-timi | @Slone123c |   |   |   |   |  
-Hash Search | <ul><li>[x] @krahets </li></ul> | @Boy-timi | @Slone123c |   |   |   |   |  
-Bubble Sort | <ul><li>[x] @krahets </li></ul> | @Boy-timi | @Slone123c | @IsChristina | @justin-tse |   |   |  
-Insertion Sort | <ul><li>[x] @krahets </li></ul> | @Boy-timi | <ul><li>[x] @msk397 </li></ul> | @IsChristina | @justin-tse |   |   |  
-Quick Sort | <ul><li>[x] @krahets </li></ul> | @Boy-timi | <ul><li>[x] @msk397 </li></ul> | @IsChristina | @justin-tse |   |   |  
-Merge Sort | <ul><li>[x] @krahets </li></ul> | @Boy-timi | <ul><li>[x] @msk397 </li></ul> | @IsChristina | @justin-tse |   |   |  
diff --git a/docs/chapter_tree/avl_tree.assets/right_rotate_step1.png b/docs/chapter_tree/avl_tree.assets/right_rotate_step1.png
index 6337ad54..c7981263 100644
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