很简单，如何实现？

1<input name="mm" type="checkbox" value="a"/>

1<br/>

1<input name="mm" type="checkbox" value="b"/>

1<br/>

1<input name="mm" type="checkbox" value="c"/>

1<br/>

1<input name="mm" type="checkbox" value="d"/>

1<br/>

1<input name="mm" type="checkbox" value="e"/>

1<br/>

1<br/>

1<br/>

1<input onclick="cc(this)" type="checkbox"/>

1<script language="Javascript">   
2function cc(e)   
3{   
4var a = document.getElementsByName("mm");   
5for (var i=0; i<a.length; i++) a[i].checked = e.checked;   
6}   
7</script>

1<form name="form1">
2<select multiple="" name="list">
3<option value="1">1</option>
4<option value="2">2</option>
5<option value="3">3</option>
6</select>
7<input onclick="chAll(this)" type="checkbox"/>全选？   
8</form>

1<script language="JavaScript"><!--   
2function chAll(m)   
3{   
4var e = document.form1.list;   
5for (var i=0; i<e.options.length; i++)   
6e.options[i].selected = m.checked;   
7}   
8//--></script>