diff --git a/2021/2021-03-18_basicGitTraining/slides/essential_commands.md b/2021/2021-03-18_basicGitTraining/slides/essential_commands.md
index 9abebff7f5b9e15c835f9d3445446fdead5deef0..982f1a4e4c550a0471c23609971e6a49ac13c596 100644
--- a/2021/2021-03-18_basicGitTraining/slides/essential_commands.md
+++ b/2021/2021-03-18_basicGitTraining/slides/essential_commands.md
@@ -74,7 +74,11 @@ $ git status
 ```bash
 $ git diff
 ```
-exit with `q`
+exit with `q`.
+
+<br>
+
+![bulb](slides/img/bulb.png)  If it is a long diff, you can display additional lines with space.