Corrections for a/an in code comments and documentation
diff --git a/Lib/lib-tk/Tkinter.py b/Lib/lib-tk/Tkinter.py
index cc657fa..e825afa 100644
--- a/Lib/lib-tk/Tkinter.py
+++ b/Lib/lib-tk/Tkinter.py
@@ -1252,7 +1252,7 @@
         # time field: "valid for events that contain a time field"
         # width field: Configure, ConfigureRequest, Create, ResizeRequest,
         # and Expose events only
-        # x field: "valid for events that contain a x field"
+        # x field: "valid for events that contain an x field"
         # y field: "valid for events that contain a y field"
         # keysym as decimal: KeyPress and KeyRelease events only
         # x_root, y_root fields: ButtonPress, ButtonRelease, KeyPress,
diff --git a/Lib/test/test_imageop.py b/Lib/test/test_imageop.py
index 9589bf2..50ad4e7 100644
--- a/Lib/test/test_imageop.py
+++ b/Lib/test/test_imageop.py
@@ -121,7 +121,7 @@
         print 'grey2rgb'
     image = imageop.grey2rgb(greyimage, width, height)
 
-    # Convert a 8-bit deep greyscale image to a 1-bit deep image by
+    # Convert an 8-bit deep greyscale image to a 1-bit deep image by
     # thresholding all the pixels. The resulting image is tightly packed
     # and is probably only useful as an argument to mono2grey.
     if verbose: