function show_sub1()
{
  sub1.style.visibility="visible";
}

function hide_sub1()
{
  sub1.style.visibility="hidden"
}

function show_sub2()
{
  sub2.style.visibility="visible";
}

function hide_sub2()
{
  sub2.style.visibility="hidden";
}

function show_sub3()
{
  sub3.style.visibility="visible";
}

function hide_sub3()
{
  sub3.style.visibility="hidden";
}

function show_sub4()
{
  sub4.style.visibility="visible";
}

function hide_sub4()
{
  sub4.style.visibility="hidden";
}

function show_sub5()
{
  sub5.style.visibility="visible";
}

function hide_sub5()
{
  sub5.style.visibility="hidden";
}

function show_sub6()
{
  sub6.style.visibility="visible";
}

function hide_sub6()
{
  sub6.style.visibility="hidden";
}

function show_sub7()
{
  sub7.style.visibility="visible";
}

function hide_sub7()
{
  sub7.style.visibility="hidden";
}