Query String

when i use the following code on button release action script. it send all three variables with query string.

My question is how can i send specific variable with query string not all variable for example i just want to send city varaible only. how. help plzzzzzzzzzzzzzzzz

on (release) {

var myVar1:age = myAge;
var myVar1:name = myCountry;
var myVar1:city = myCity;

getURL(“test.php”, “_self”, “GET”);

}