谁能帮我解释一下这些AS代码

var _key = {};

//状态
var _time = 200;
//间隔时间
var right = 68;
var left = 65;
var up = 87;
var down = 83;
var hit = 74;
var onEnterFrame = function () {
// trace(state+"——————状态");
if (Key.isDown(right) and !Key.isDown(left) and !Key.isDown(hit)) {
u_press = true;
d_press = true;
// trace("右");
man._xscale = 100;
if (!r_press) {
r_press = true;
if (getTimer()-r_time<_time and Key.getCode() == right) {
state = "run";
man.gotoAndPlay(state);
speed = 20;
} else {
r_time = getTimer();
state = "walk";
man.gotoAndPlay(state);
speed = 5;
}
}
man._x += speed;
}