diff --git a/cc/operators/ops.h b/cc/operators/ops.h
index e5a1e97..3483526 100644
--- a/cc/operators/ops.h
+++ b/cc/operators/ops.h
@@ -10,7 +10,7 @@ namespace operators {
 
 template<typename T>
 T mul(T a, T b) {
-    return a * b; // 请修改这里的return语句
+    return a * b; // 请修改这里的return语句.
 }
 
 template<typename T>