51help TIY
码：
<!DOCTYPE html> <html> <head> <script type="text/javascript" src="../jquery/jquery.js" tppabs="http://www.51help.tk/jquery/jquery.js"></script> </head> <body> <ul class="level-1"> <li class="item-i">I</li> <li class="item-ii">II <ul class="level-2"> <li class="item-a">A</li> <li class="item-b">B <ul class="level-3"> <li class="item-1">1</li> <li class="item-2">2</li> <li class="item-3">3</li> </ul> </li> <li class="item-c">C</li> </ul> </li> <li class="item-iii">III</li> </ul> <script>$('ul.level-2').children().css('background-color', 'red');</script> </body> </html>
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