as for frame1:

i=1;//定义变量初值
_root.mc._visible=false;//让父电影剪辑不可见


as for frame2:


if (i<=2000) {
//i的变化范围
mc.duplicateMovieClip("mc"+i, i);
//复制子电剪，深度为i
_root["mc"+i]._x = random(550);
_root["mc"+i]._y = random(400);
_root["mc"+i]._alpha = random(100);
//设置子电剪的坐标和透明度
_root["mc"+i].onEnterFrame = function() {
this._y += 3;
};//让每一个子电剪的纵向坐标不断加3
i++;
}


as for frame3:

gotoAndPlay(2);//让播放头播放第二贞