Flash可以检测多少个按键？使用as3

private function onKeyDown(event:KeyboardEvent):void {
        //moviment keys
        if (event.keyCode == 37 || event.keyCode == 65) {
            this.leftKeyPressed = true;
        }
        if (event.keyCode == 39 || event.keyCode == 68) {
            this.rightKeyPressed = true;
        }
        if (event.keyCode == 38 || event.keyCode == 87) {
            this.upKeyPressed = true;
        }
        if (event.keyCode == 40 || event.keyCode == 83) {
            this.downKeyPressed = true;
        }

        if (event.keyCode == this.shootKey) {
            this.shootKeyPressed = true;
        }
    }

onKeyUp事件：

private function onKeyUp(event:KeyboardEvent):void {
        if (event.keyCode == 37 || event.keyCode == 65) {
            this.leftKeyPressed = false;
        }
        if (event.keyCode == 39 || event.keyCode == 68) {
            this.rightKeyPressed = false;
        }
        if (event.keyCode == 38 || event.keyCode == 87) {
            this.upKeyPressed = false;
        }
        if (event.keyCode == 40 || event.keyCode == 83) {
            this.downKeyPressed = false;
        }
        if (event.keyCode == this.shootKey) {
            this.shootKeyPressed = false;
        }
        if (event.keyCode == changeColorKey) {
            trace('color key released');
            trace(getTimer());
            this.changeColorKeyPressed = true;
        }

    }

基本上,几乎所有时间都会由玩家按住shootKey.并且会经常按下changeColorKey但不会按下.在测试时我注意到持有shootKey和右箭头,changeColorKey的onKeyUp事件不会被触发.按住向上或向下箭头键而不是向右箭头具有相同的效果.如果我按住左箭头键,事件就会被触发.它为什么会出现？我的代码有问题吗？