fix typos/rephrase
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 2b9a679..b491c78 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -400,12 +400,12 @@
does not have to hold true for third-party extensions as it is implementation
specific.
- The *default* argument allows to define a value which will be returned
- if the object type does not provide means to retrieve the size and would
- cause a `TypeError`.
+ If given, *default* will be returned if the object does not provide means to
+ retrieve the size. Otherwise a `TypeError` will be raised.
- :func:`getsizeof` calls the object's __sizeof__ method and adds an additional
- garbage collector overhead if the object is managed by the garbage collector.
+ :func:`getsizeof` calls the object's ``__sizeof__`` method and adds an
+ additional garbage collector overhead if the object is managed by the garbage
+ collector.
.. versionadded:: 2.6