Wording fix.
diff --git a/Doc/library/concurrent.futures.rst b/Doc/library/concurrent.futures.rst
index 0cb170b..e5d13f3 100644
--- a/Doc/library/concurrent.futures.rst
+++ b/Doc/library/concurrent.futures.rst
@@ -221,7 +221,7 @@
.. method:: cancel()
Attempt to cancel the call. If the call is currently being executed and
- cannot be cancelled and the method will return ``False``, otherwise the
+ cannot be cancelled then the method will return ``False``, otherwise the
call will be cancelled and the method will return ``True``.
.. method:: cancelled()