function chkdiv(divid){ var chkid=document.getElementById(divid); if(chkid != null){return true; } else {return false; } } if (chkdiv('fy')){ document.getElementById('fy').innerHTML='上一篇:沪科版《DNA复制和蛋白质合成》教学案汇编 下一篇:英语:life in the future Reading 课件 '; }