单选钮控制文本框解决方法

单选钮控制文本框
请问  
  <input   type= "radio "   name= "typestate "   value= "0 "> 国际
<input   type= "radio "   name= "typestate "   value= "1 "   checked> 国内
当我选择国际时   显示一个文本框填写，但我选择国内是，出现一个下拉菜单选择省会。选择其一时，其二就隐藏了。       请问大虾们怎么写js

------解决方案--------------------
<div>


<input type= "radio " name= "t " value= "0 " onclick= "arg() "> 国际

<input id= "u " style= "display:none "> <p>


<input type= "radio " name= "t " value= "1 " onclick= "arg() " checked> 国内

<select id= "g ">
<option value= " "> 请选择 </option>
</select>

<div>


<script language= "JavaScript ">

var arg = function (){

if (t[0].checked)
{
u.style.display = " " ;

g.style.display = "none " ;
}
else
{
u.style.display = "none " ;

g.style.display = " " ;
}


}

</script>