gh-85747: "Preface" section of asyncio-eventloop.rst: Switch to activ…

…e voice and suggest other edits (GH-99784)

(cherry picked from commit bf26bdf)

Co-authored-by: Brian Skinn <brian.skinn@gmail.com>

Doc/library/asyncio-eventloop.rst

@@ -33,7 +33,8 @@ an event loop:
 
    Return the running event loop in the current OS thread.
 
-   If there is no running event loop a :exc:`RuntimeError` is raised.
+   Raise a :exc:`RuntimeError` if there is no running event loop.
+
    This function can only be called from a coroutine or a callback.
 
    .. versionadded:: 3.7
@@ -52,17 +53,19 @@ an event loop:
    :func:`get_running_loop` function is preferred to :func:`get_event_loop`
    in coroutines and callbacks.
 
-   Consider also using the :func:`asyncio.run` function instead of using
-   lower level functions to manually create and close an event loop.
+   As noted above, consider using the higher-level :func:`asyncio.run` function,
+   instead of using these lower level functions to manually create and close an
+   event loop.
 
    .. deprecated:: 3.10
-      Deprecation warning is emitted if there is no running event loop.
-      In future Python releases, this function will be an alias of
-      :func:`get_running_loop`.
+      Emits a deprecation warning if there is no running event loop.
+      In future Python releases, this function may become an alias of
+      :func:`get_running_loop` and will accordingly raise a
+      :exc:`RuntimeError` if there is no running event loop.
 
 .. function:: set_event_loop(loop)
 
-   Set *loop* as a current event loop for the current OS thread.
+   Set *loop* as the current event loop for the current OS thread.
 
 .. function:: new_event_loop()