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','大一'],

             ['小J','男','20','大三']

            ];

for( var j=0;j<infos.length;j++){

//筛选大一

     switch(infos[j][3]){

         case '大一':

             {

//筛选女生

                 switch(infos[j][1]){

                     case '女':

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

                    default:

                         continue;

                 }

             }

             default:

             continue;

     }

 }