var infos=new Array()；

 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","大一"],["小J","男","20","大三"]

]；

 //第一步把之前的数据写成一个数组的形式,定义变量为 infos

 //第一次筛选，找出都是大一的信息

for(var i=0;i<infos.length;i++){

  if(info[i][3]=='大一'){

  document.write("大一学生的名字:"+infos[i][0])+"<br/>");

  }

 }

 //第二次筛选，找出都是女生的信息

 for(var j=0;j<infos.length;j++){

 if((infos[j][3]=='大一')&&(infos[j][1]=='女')){

   document.write("大一女生的名字:"+infos[j][0])+"<br/>");

 }

 }