Best solution to this would be to additionally host a copy of jQuery locally, and fall back to that copy if the original isn't loaded:
<script>window.jQuery || document.write('<script src="js/libs/jquery-1.7.2.min.js"></script>')</script>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script type="text/javascript">window.jQuery || document.write('<script src="js/jquery-1.7.2.min.js">\x3C/script>')</script>
connect to ajax.googleapis.com first will block long time until time out
now, i add "127.0.0.1 ajax.googleapis.com" to /etc/hosts
but this is not friend for new users in china
why not use jquery in locally host or other free cdn
http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.7.2.min.js