<input name="a" type="radio" value="挂号信" onclick="this.form.textfield.value=this.value">挂号信接收
<input name="a" type="radio" value="email" onclick="this.form.textfield.value=this.value">email接收
<input type="text" name="textfield" value="">
<input name="a" type="radio" value="email" onclick="this.form.textfield.value=this.value">email接收
<input type="text" name="textfield" value="">
<form name=form1>
<input name="" type="radio" value="挂号信" onclick=form1.textfield.value="挂号信">挂号信接收
<input name="" type="radio" value="email" onclick=form1.textfield.value="email接收">email接收
<input type="text" name="textfield" value="">
</form>
<body>
<input type="radio" value="email" onclick="textfield.value=this.value">email接收
<input type="text" name="textfield" value="">