diff --git a/concurrency/concurrency_v1/chapter2/2_5_id.cpp b/concurrency/concurrency_v1/chapter2/2_5_id.cpp
index 67b00d7..905aafb 100644
--- a/concurrency/concurrency_v1/chapter2/2_5_id.cpp
+++ b/concurrency/concurrency_v1/chapter2/2_5_id.cpp
@@ -27,8 +27,12 @@ void some_core_part_of_algorithm() {
 }
 
 int main() {
-    std::cout << std::this_thread::get_id() << endl;
+    master_thread = std::this_thread::get_id();
+    std::cout << "master_thread: " << master_thread << endl;
+    cout << "master_thread 中运行:" << endl;
+    some_core_part_of_algorithm();
+    cout << "thread 中运行:" << endl;
     thread t(some_core_part_of_algorithm);
     t.join();
     return 0;
-}
\ No newline at end of file
+}