如果有看懂的话，麻烦你能否将主要的语句解释一下：(主要说明它们的功能。）

document.write("")
document.write('')

var master = new Object("element")
master.curLeft = -100;
master.curTop = 10;

function moveAlong(layerName, paceLeft, paceTop, fromLeft, fromTop){
clearTimeout(eval(layerName).timer)
if(eval(layerName).curLeft != fromLeft){
if((Math.max(eval(layerName).curLeft, fromLeft) - Math.min(eval(layerName).curLeft, fromLeft)) < paceLeft){eval(layerName).curLeft = fromLeft}
else if(eval(layerName).curLeft < fromLeft){eval(layerName).curLeft = eval(layerName).curLeft + paceLeft}
else if(eval(layerName).curLeft > fromLeft){eval(layerName).curLeft = eval(layerName).curLeft - paceLeft}
document.all[layerName].style.left = eval(layerName).curLeft
}
if(eval(layerName).curTop != fromTop){
if((Math.max(eval(layerName).curTop, fromTop) - Math.min(eval(layerName).curTop, fromTop)) < paceTop){eval(layerName).curTop = fromTop}
else if(eval(layerName).curTop < fromTop){eval(layerName).curTop = eval(layerName).curTop + paceTop}
else if(eval(layerName).curTop > fromTop){eval(layerName).curTop = eval(layerName).curTop - paceTop}
document.all[layerName].style.top = eval(layerName).curTop
}
eval(layerName).timer=setTimeout('moveAlong("'+layerName+'",'+paceLeft+','+paceTop+','+fromLeft+','+fromTop+')',30)
}

function setPace(layerName, fromLeft, fromTop, motionSpeed){
eval(layerName).gapLeft = (Math.max(eval(layerName).curLeft, fromLeft) - Math.min(eval(layerName).curLeft, fromLeft))/motionSpeed
eval(layerName).gapTop = (Math.max(eval(layerName).curTop, fromTop) - Math.min(eval(layerName).curTop, fromTop))/motionSpeed
moveAlong(layerName, eval(layerName).gapLeft, eval(layerName).gapTop, fromLeft, fromTop)
}

var expandState = 0
function expand(){
if(expandState == 0){setPace("master", 0, 10, 10);
document.menutop.src = "images/menub.gif"; expandState = 1;}
else{
setPace("master", -100, 10, 10);
document.menutop.src = "images/menu.gif"; expandState = 0;}
}
document.write("");
var sidemenu = document.all.master;

function yuzi(){
sidemenu.style.top = document.body.scrollTop+10
}
setInterval("yuzi()",100);