Question

I am not sure if this is a html or javascript tech.
I want to achieve like that, only show two select boxes,
once I clicked India, another select box will shows only Indiacities options name="listtwo" id="listtwo", if clicked US, shows us cities options.
Could someone please give an example. Many thanks

India
US
Germany

    <select name="listtwo" id="listtwo">
        <option value="Indiacity1">Indiacity1</option>
        <option value="Indiacity2">Indiacity1</option>
        <option value="Indiacity3">Indiacity1</option>
    </select>

  <select name="list3" id="list3">
        <option value="Germany1">Germany1</option>
        <option value="Germany2">Germany1</option>
        <option value="Germany3">Germany1</option>
    </select>

<select name="list4" id="list4">
        <option value="US1">US1</option>
        <option value="US2">US1</option>
        <option value="US3">US1</option>
    </select>​

Answer 1

HTML:

<select id="country-select">
    <option>--- Select One ---</option>
    <option value="us">US</option>
    <option value="germany">Germany</option>
</select>

<select id="us-select" class="sub-menu hide">
    <option value="austin">Austin</option>
</select>

<select id="germany-select" class="sub-menu hide">
    <option value="berlin">Berlin</option>
</select>​

CSS:

.hide {
    display: none;            
}​

jQuery:

$('#country-select').change(function (e) {
    $('.sub-menu').hide();
    var selectedCountry = $(this).val();
    if (selectedCountry) {
        $('#' + selectedCountry + '-select').show();
    }       
});​

And the Fiddle for anyone to check out: http://jsfiddle.net/RPWPZ/3/

Of course you would have to add all the items for India, and any other countries you’ll be caring about.

Edit: if you want a country selected when the page loads, look at the changes in this Fiddle: http://jsfiddle.net/RPWPZ/5/