var fruits:Array = ['apple', 'lemon', 'banana', 'orange', 'mandarin', 'lime', 'kiwi', 'pear', 'apricot'];
var texts:Array = [];           // array to put your text fields
var first_time:Boolean = true;  // indicates if it's the first enter

for(var i:int = 0; i < fruits.length; i++){
    var text_field:TextField = new TextField();
        text_field.x = 50;
        text_field.y = 50 + 28*i;
        text_field.height = 25;
        text_field.text = fruits[i];
        text_field.border = true;
    addChild(text_field);
    texts.push(text_field);
}

stage.addEventListener(
    KeyboardEvent.KEY_DOWN,
    function (e:KeyboardEvent):void {
        if (e.keyCode == Keyboard.ENTER){
            if(first_time){
                first_time = false;
                var index:int = Math.round(Math.random()*fruits.length);
                for(var i:int = 0; i<fruits.length; i++){
                    if(i != index){
                        // if it's not the randomly selectected text field, then set its text to "good luck"
                        texts[i].text = 'good luck';
                    }
                }
            } else {
                // if you want repeat again, set first_time = true
                //first_time = true;
                for(i = 0; i < fruits.length; i++){
                    // reset all text fields
                    texts[i].text = fruits[i];
                }
            }
        }
    }
)