flash actionScript

import fl.motion.MotionEvent;
import flash.media.Sound;
import flash.net.URLRequest;
import flash.display.SimpleButton;
import flash.media.SoundChannel;
import flash.display.Sprite;
import flash.events.*;




var dizhi:URLRequest = new URLRequest("/EbookFlash/book_1/Page034/Zoom_In_SB1_Track_19.mp3");

var shengyin:Sound = new Sound();
var channel:SoundChannel;
var position:int = 0;
var is_play = false;
shengyin.load(dizhi);
btu_stop.visible = false;
btu_play.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler);

function fl_MouseClickHandler(event:MouseEvent):void
{
channel = shengyin.play(position);
is_play = true;
btu_play.visible = false;
btu_stop.visible = true;
channel.addEventListener(Event.SOUND_COMPLETE, soundCompleteHandler);
}
btu_stop.addEventListener(MouseEvent.CLICK, f2_MouseClickHandler);