diff --git a/app.py b/app.py
index c3959a8..7ac9095 100644
--- a/app.py
+++ b/app.py
@@ -1,6 +1,9 @@
-def greet(name: str) -> str:
+def greet(name: str, lang: str = "en") -> str:
+    if lang == "zh":
+        return f"你好,{name}!"
     return f"Hello, {name}!"
 
 
 if __name__ == "__main__":
     print(greet("world"))
+    print(greet("世界", lang="zh"))