How can I pass more parameters with AJAX

I have the following:

$('#TopicDescription').change(function () {
            $.ajax({
                url: "/adminQuestions/GetSubTopics",
                data: $('#TopicDescription').val(),
                success: function (data) {
                    $('#SubTopicDescription').html(data);
                }
            });
        });

This works good but I would like to pass another parameter. Can someone explain how I can do this. Also in the GetSubTopics method will the parameter passed be referenced by the word "d开发者_StackOverflow中文版ata" and is there a connection between data: and the .html(data).

Sorry if my question is confusing.

Beverly

pass an object in data:

data: {
    foo : 10,
    bar : 42
}

$.ajax({
    url: "/adminQuestions/GetSubTopics",
    data: { v1: $('#element1').val(),
            v2: $('#element2').val(),
            v3: $('#element3').val()
        },
    success: function(msg) {
        // do something with msg
    }
});

Data to be sent to the server. It is converted to a query string, if not already a string. It's appended to the url for GET-requests. See processData option to prevent this automatic processing. Object must be Key/Value pairs. If value is an Array, jQuery serializes multiple values with same key based on the value of the traditional setting (described below).

I hope this helps.
Hristo