diff --git a/shell/shell变量提取赋值.md b/shell/shell变量提取赋值.md
index ff713e5..fce489f 100644
--- a/shell/shell变量提取赋值.md
+++ b/shell/shell变量提取赋值.md
@@ -1,5 +1,5 @@
-|-|-|
 |表达式|含义|
+|-|-|
 |${var:-aa}|若var为空或未设定, 返回aa, var值不变|
 |${var:=aa}|若var为空或未设定, 返回aa, var=aa|
 |${var:+aa}|若var有值 返回aa, var值不变|