for(var i=0;i<5;i++){
     infos[i] = new Array();
     for(var j=0;j<2;j++){
         infos[i][j] = info[num];
         num++;
         if(infos[i][j][3]== "大一"){
             document.write(infos[i][j]);
             document.write("<br />");
             info[key] = infos[i][j];
             key++;
         }

这个不懂啊。什么意思呢