diff --git a/docs/book/10-Interfaces.md b/docs/book/10-Interfaces.md
index aff455e..754d18d 100644
--- a/docs/book/10-Interfaces.md
+++ b/docs/book/10-Interfaces.md
@@ -1299,7 +1299,7 @@ import java.nio.*;
 import java.util.*;
 
 public class RandomStrings implements Readable {
-    private statdic Random rand = new Random(47);
+    private static Random rand = new Random(47);
     private static final char[] CAPITALS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
     private static final char[] LOWERS = "abcdefghijklmnopqrstuvwxyz".toCharArray();
     private static final char[] VOWELS = "aeiou".toCharArray();
@@ -1815,4 +1815,4 @@ Chess move 3
 
 <!-- 分页 -->
 
-<div style="page-break-after: always;"></div>
\ No newline at end of file
+<div style="page-break-after: always;"></div>