<select onchange="if(this.value!=''){txt.disabled=false;txt.value=this.value}else txt.disabled=true">
<option value="">请选择
<option value=aa>aa
<option value=bb>bb
<option value=cc>cc</select><input name=txt disabled>
<option value="">请选择
<option value=aa>aa
<option value=bb>bb
<option value=cc>cc</select><input name=txt disabled>
<SCRIPT LANGUAGE=javascript>
<!--
function chg(){
var intC=oSearchText.selectedIndex;
var o=document.getElementsByTagName("input");
for(var i=0;i<o.length;i++){
if(i!=intC)
o[i].readOnly=true;
else
o[i].readOnly=false;
}
}
//-->
</SCRIPT>
</HEAD>
<BODY>
<SELECT id=oSearchText onchange="chg()">
<OPTION value=a selected>a
<OPTION value=b>b
<OPTION value=c>c
</SELECT><INPUT type="text" id=aa name=aa ><BR>
<INPUT type="text" id=bb name=bb readOnly><BR>
<INPUT type="text" id=cc name=cc readOnly><BR>
</BODY>
<SCRIPT LANGUAGE=javascript>
<!--
function chg(){
var intC=oSearchText.selectedIndex;
var o=document.getElementsByTagName("input");
for(var i=0;i<o.length;i++){
if(i!=intC)
o[i].readOnly=true;
else
o[i].readOnly=false;
}
}
//-->
</SCRIPT>
</HEAD>
<BODY>
<SELECT id=oSearchText onchange="chg()">
<OPTION value=a selected>a
<OPTION value=b>b
<OPTION value=c>c
</SELECT><INPUT type="text" id=aa name=aa ><BR>
<INPUT type="text" id=bb name=bb readOnly><BR>
<INPUT type="text" id=cc name=cc readOnly><BR>
</BODY>