diff --git a/README-zh_CN.md b/README-zh_CN.md
index b838ab7..789b57e 100644
--- a/README-zh_CN.md
+++ b/README-zh_CN.md
@@ -1140,6 +1140,8 @@ npm install --save-dev @types/library-name
 
 即使在 JavaScript 文件中，您也可以通过 `// @ts-check` 使用环境声明。
 
+`declare` 关键字可以为现有的 JavaScript 代码启用类型定义，而无需导入它，作为来自另一个文件或全局的类型的占位符。
+
 ### 属性检测和多余属性检测
 
 TypeScript 基于结构类型系统，但过多的属性检查是 TypeScript 的一个属性，它允许它检查对象是否具有类型中指定的确切属性。
diff --git a/README.md b/README.md
index 2b70ec5..3f28e5b 100644
--- a/README.md
+++ b/README.md
@@ -1145,6 +1145,8 @@ For your defined Ambient Declarations, you can import using the "triple-slash" r
 
 You can use Ambient Declarations even within JavaScript files using `// @ts-check`.
 
+The `declare` keyword enables type definitions for existing JavaScript code without importing it, serving as a placeholder for types from another file or globally.
+
 ### Property Checking and Excess Property Checking
 
 TypeScript is based on a structural type system but excess property checking is a property of TypeScript which allows it to check whether an object has the exact properties specified in the type.
diff --git a/downloads/typescript-book-zh_CN.epub b/downloads/typescript-book-zh_CN.epub
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diff --git a/website/src/content/docs/book/exploring-the-type-system.md b/website/src/content/docs/book/exploring-the-type-system.md
index 4b398f7..3616873 100644
--- a/website/src/content/docs/book/exploring-the-type-system.md
+++ b/website/src/content/docs/book/exploring-the-type-system.md
@@ -503,6 +503,8 @@ For your defined Ambient Declarations, you can import using the "triple-slash" r
 
 You can use Ambient Declarations even within JavaScript files using `// @ts-check`.
 
+The `declare` keyword enables type definitions for existing JavaScript code without importing it, serving as a placeholder for types from another file or globally.
+
 ### Property Checking and Excess Property Checking
 
 TypeScript is based on a structural type system but excess property checking is a property of TypeScript which allows it to check whether an object has the exact properties specified in the type.
diff --git a/website/src/content/docs/zh-cn/book/exploring-the-type-system.md b/website/src/content/docs/zh-cn/book/exploring-the-type-system.md
index 6b2a88f..63f83f0 100644
--- a/website/src/content/docs/zh-cn/book/exploring-the-type-system.md
+++ b/website/src/content/docs/zh-cn/book/exploring-the-type-system.md
@@ -506,6 +506,8 @@ npm install --save-dev @types/library-name
 
 即使在 JavaScript 文件中，您也可以通过 `// @ts-check` 使用环境声明。
 
+`declare` 关键字可以为现有的 JavaScript 代码启用类型定义，而无需导入它，作为来自另一个文件或全局的类型的占位符。
+
 ### 属性检测和多余属性检测
 
 TypeScript 基于结构类型系统，但过多的属性检查是 TypeScript 的一个属性，它允许它检查对象是否具有类型中指定的确切属性。