a = 2 // a=numbers of banners
var slump = Math.random();
var talet = Math.round(slump * (a-1))+1;
function create() {

this.width = ''
this.height = ''
this.src = ''
this.href = ''
this.border = ''
this.alt = ''
}

b = new Array()
for(var i=1; i<=a; i++) { b[i] = new create() }
b[1].src = "http://www.f1boat.com.cn/ad/banner1.jpg"
b[1].href = "http://www.f1boat.com.cn/"
b[1].width = "960"
b[1].height = "149"
b[1].border = "0"
b[1].alt = "2010F1摩托艇世界锦标赛大幕即将拉开！"

b[2].src = "http://www.f1boat.com.cn/ad/banner1.jpg"
b[2].href = "http://www.f1boat.com.cn/"
b[2].width = "960"
b[2].height = "149"
b[2].border = "0"
b[2].alt = "2010F1摩托艇世界锦标赛大幕即将拉开！"

var visa = "";

visa += '<a href="'+b[talet].href+'">'
visa += '<img src="'+b[talet].src+'" height='+b[talet].height
visa += ' width='+b[talet].width+' border='+b[talet].border+' alt='+b[talet].alt+'>';
visa += '</a>'