change_pl_a= new Image();
change_pl_a.src = "../img/index/link_pl.gif"
change_pl_b= new Image();
change_pl_b.src = "../img/index/link_pl_a.gif"

change_1_a= new Image();
change_1_a.src = "../img/nav_pl/nav_01.gif"
change_1_b= new Image();
change_1_b.src = "../img/nav_pl/nav_a_01.gif"

change_2_a= new Image();
change_2_a.src = "../img/nav_pl/nav_02.gif"
change_2_b= new Image();
change_2_b.src = "../img/nav_pl/nav_a_02.gif"

change_3_a= new Image();
change_3_a.src = "../img/nav_pl/nav_03.gif"
change_3_b= new Image();
change_3_b.src = "../img/nav_pl/nav_a_03.gif"

change_4_a= new Image();
change_4_a.src = "../img/nav_pl/nav_04.gif"
change_4_b= new Image();
change_4_b.src = "../img/nav_pl/nav_a_04.gif"