Issue #25523: Backported a-to-an corrections.
diff --git a/Doc/library/email.parser.rst b/Doc/library/email.parser.rst
index 0f99a2f..04e2334 100644
--- a/Doc/library/email.parser.rst
+++ b/Doc/library/email.parser.rst
@@ -133,7 +133,7 @@
methods on file-like objects.
The text contained in *fp* must be formatted as a block of :rfc:`2822`
- style headers and header continuation lines, optionally preceded by a
+ style headers and header continuation lines, optionally preceded by an
envelope header. The header block is terminated either by the end of the
data or by a blank line. Following the header block is the body of the
message (which may contain MIME-encoded subparts).
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index 5e3bd1c..ca91cd7 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -568,7 +568,7 @@
.. versionadded:: 2.7
Unittest supports skipping individual test methods and even whole classes of
-tests. In addition, it supports marking a test as a "expected failure," a test
+tests. In addition, it supports marking a test as an "expected failure," a test
that is broken and will fail, but shouldn't be counted as a failure on a
:class:`TestResult`.
diff --git a/Doc/library/zlib.rst b/Doc/library/zlib.rst
index 192bd4d..70e1483 100644
--- a/Doc/library/zlib.rst
+++ b/Doc/library/zlib.rst
@@ -31,7 +31,7 @@
.. function:: adler32(data[, value])
- Computes a Adler-32 checksum of *data*. (An Adler-32 checksum is almost as
+ Computes an Adler-32 checksum of *data*. (An Adler-32 checksum is almost as
reliable as a CRC32 but can be computed much more quickly.) If *value* is
present, it is used as the starting value of the checksum; otherwise, a fixed
default value is used. This allows computing a running checksum over the