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"]];

infos.forEach(function(item){

if(item[3]=="大一"){

if(item[1]=="女"){

document.write(item[0]+"<br>")

}

}

})

一維數組 var arr=[1,2,3,4];

二維數組 var arr2=[[1,2,3,4],[5,6,7,8,9,10]] ,二維只是代表一個xy矩陣

你吧那4個看成一個整體.就好比一個盒子里面裝的有4個東西.