diff --git a/cmd/classroom/dal/cache/schedule.go b/cmd/classroom/dal/cache/schedule.go
index d71668a..d322a80 100644
--- a/cmd/classroom/dal/cache/schedule.go
+++ b/cmd/classroom/dal/cache/schedule.go
@@ -1,3 +1,19 @@
+/*
+Copyright 2024 The west2-online Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
 package cache
 
 import (
diff --git a/go.mod b/go.mod
index a3a8d2c..ac00020 100644
--- a/go.mod
+++ b/go.mod
@@ -131,7 +131,7 @@ require (
 	golang.org/x/crypto v0.27.0 // indirect
 	golang.org/x/net v0.29.0 // indirect
 	golang.org/x/oauth2 v0.21.0 // indirect
-	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sync v0.8.0
 	golang.org/x/sys v0.25.0 // indirect
 	golang.org/x/text v0.18.0 // indirect
 	golang.org/x/time v0.6.0