diff --git a/en/02.5.md b/en/02.5.md
index cc50b8af..38acb66b 100644
--- a/en/02.5.md
+++ b/en/02.5.md
@@ -204,7 +204,7 @@ We define some constants and customized types.
 
 Then we defined some methods for our customized types.
 
-- Volume() uses Box as its receiver and returns volume of Box.
+- Volume() uses Box as its receiver and returns the volume of Box.
 - SetColor(c Color) changes Box's color.
 - BiggestsColor() returns the color which has the biggest volume.
 - PaintItBlack() sets color for all Box in BoxList to black.