No key is pressed?

how do i tell flash to go to a certian state when neither of 2 keys is pressed?

see, i have this game and i need the charachter to go into a state of idleness when no key is being pressed. i also belive that this could be done with speed but i am a newbie.

here is the code.

onClipEvent (load) {
fall = false;
_name = "circle";
jump = 0;
speed = 6;
jumpheight = 12;
maxfall = -54;
}
onClipEvent (enterFrame) {
xmin = getBounds(_root).xMin;
xmax = getBounds(_root).xMax;
ymin = getBounds(_root).yMin;
ymax = getBounds(_root).yMax;
if (Key.isDown(Key.SPACE) && fall == false && jump == undefined) {
fall = true;
jump = jumpheight;
gotoAndStop("jump")
}
if (jump<>undefined) {
if (jump>maxfall) {
jump--;
}
_y -= jump;
}
}
onClipEvent (enterFrame) {
if (Key.isDown(Key.LEFT)) {
_x -= speed;
gotoAndStop("left")
}
if (Key.isDown(Key.RIGHT)) {
_x += speed;
gotoAndStop("right")
}
}

if you need more information just ask