为什么图片显示不出来呢？

Question

var bannerImage=new Array();
bannerImage[0]="'/index2/img/cool (1).png'";
bannerImage[1]="'/index2/img/cool (2).jpg'";
bannerImage[2]="'/index2/img/cool (2).png'";
bannerImage[3]="'/index2/img/cool (3).png'";
bannerImage[4]="'/index2/img/cool (3).jpg'";
bannerImage[5]="'/index2/img/cool (4).png'";
bannerImage[6]="'/index2/img/cool (4).jpg'";
var randomImageIndex=Math.round(Math.random()*6);
document.write("<img src=bannerImage[randomImageIndex]/>")