I think I may have figured it out. The latest version of IE is 9, and in the template, for the survey, the IE version only ranges from 6 to 8, so if I add this
<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
<title>{SURVEYNAME}</title>
<meta name="generator" content="LimeSurvey
www.limesurvey.org" />
<!-- The following line includes template.css and if an RTL-language is used template-rtl.css -->
{TEMPLATECSS}
<!--[if lte IE 6]>
<link rel="stylesheet" type="text/css" href="{TEMPLATEURL}ie_fix_6.css" />
<![endif]-->
<!--[if IE 7]>
<link rel="stylesheet" type="text/css" href="{TEMPLATEURL}ie_fix_7.css" />
<![endif]-->
<!--[if IE 8]>
<link rel="stylesheet" type="text/css" href="{TEMPLATEURL}ie_fix_8.css" />
<![endif]-->
<!--[if lte IE 9]>
<link rel="stylesheet" type="text/css" href="{TEMPLATEURL}ie_fix_9.css" />
<![endif]-->
It might fix the problem.