var.infos
     ['小A','女',21,'大一'],
     ['小B','男',23,'大三'],
     ['小C','男',24,'大四'],
     ['小D','女',21,'大一'],
     ['小E','女',22,'大四'],
     ['小F','男',21,'大一'],
     ['小G','女',22,'大二'],
     ['小H','女',20,'大三'],
     ['小I','女',20,'大三'],
     ['小J','女',20,'大三']
     for(var i=1;i<infos.length;i++)
       if(infos[i][3] === "大一" && infos[i][1] === "女") {
     document.write(infos[i][0] + "<br />");
         }