diff --git a/classroom/classroom.c b/classroom/classroom.c
index 0b42044..dd3121b 100644
--- a/classroom/classroom.c
+++ b/classroom/classroom.c
@@ -3,4 +3,8 @@ uint16_t remain_classroom;
 void cs_check_remain_classroom(void)
 {
 	return remain_classroom;
+}
+void cs_book_classroom(void)
+{
+	
 }
\ No newline at end of file