diff --git a/index.ts b/index.ts
index 178ccdc9ecb04d61269e97c493e6e81e3ef903f6..80a085f2f4cffab3ac5965721b346ce8783f5efa 100644
--- a/index.ts
+++ b/index.ts
@@ -24,3 +24,8 @@ let names: Array<string> = ["Alice", "Bob", "Charlie"];
 // 元组类型注释
 let tuple: [string, number] = ["Alice", 30];
 
+
+
+// 布尔值（Boolean）
+let isDone: string ;
+console.log(isDone);
diff --git a/tsconfig.json b/tsconfig.json
index 32f76b79c6f36e9bed32de3435d3dee31bcae30d..f2b783cdc6369ed768c7dd2218a613c989e731f4 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -25,7 +25,7 @@
 		/* Strict Type-Checking Options */
 		"strict": true, /* Enable all strict type-checking options. */
 		// "noImplicitAny": true,                       /* Raise error on expressions and declarations with an implied 'any' type. */
-		// "strictNullChecks": true,                    /* Enable strict null checks. */
+		"strictNullChecks": false,                    /* Enable strict null checks. */
 		// "strictFunctionTypes": true,                 /* Enable strict checking of function types. */
 		// "strictBindCallApply": true,                 /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
 		// "strictPropertyInitialization": true,        /* Enable strict checking of property initialization in classes. */