diff --git a/4.2作业.py b/4.2作业.py
new file mode 100644
index 0000000..a7f989a
--- /dev/null
+++ b/4.2作业.py
@@ -0,0 +1,15 @@
+import re
+
+phone_book = '''
+张三：138-1999-9101
+李四：139-1998-5678
+王五：138-1997-1234
+'''
+
+pattern = r'(\d{3})-(\d{4})-(\d{4})'
+
+def mask_phone(match):
+    return f'{match.group(1)}-****-{match.group(3)}'
+
+masked = re.sub(pattern, mask_phone, phone_book)
+print(masked)
\ No newline at end of file
diff --git a/4.2作业2.py b/4.2作业2.py
new file mode 100644
index 0000000..e69de29