function tm1( a )     //变化.
{
  if(a == "list01"){
  list01.style.display = 'block';
  list02.style.display = 'none';
  document.main01.src='images/ly_49.jpg';
  document.main02.src='images/ly_51.jpg';
  }
  if(a == "list02"){
  list01.style.display = 'none';
  list02.style.display = 'block';
  document.main01.src='images/cc_51.jpg';
  document.main02.src='images/cc_50.jpg';
  }
}

function tm2( b )     //变化.
{
  if(b == "layer01"){
  layer01.style.display = 'block';
  layer02.style.display = 'none';
  document.pic1.src='images/ly_77.jpg';
  document.pic2.src='images/ly_79.jpg';
  }
  if(b == "layer02"){
  layer01.style.display = 'none';
  layer02.style.display = 'block';
  document.pic1.src='images/cc_80.jpg';
  document.pic2.src='images/cc_77.jpg';
  }
}

function tm3( c )     //变化.
{
  if(c == "cen01"){
  cen01.style.display = 'block';
  cen02.style.display = 'none';
  cen03.style.display = 'none';
  cen04.style.display = 'none';
  document.getElementById("s1").className="bt1"
  document.getElementById("s2").className="bt2"
  document.getElementById("s3").className="bt2"
  document.getElementById("s4").className="bt2"
  }
  if(c == "cen02"){
  cen01.style.display = 'none';
  cen02.style.display = 'block';
  cen03.style.display = 'none';
  cen04.style.display = 'none';
  document.getElementById("s1").className="bt2"
  document.getElementById("s2").className="bt1"
  document.getElementById("s3").className="bt2"
  document.getElementById("s4").className="bt2"
  }
    if(c == "cen03"){
  cen01.style.display = 'none';
  cen02.style.display = 'none';
  cen03.style.display = 'block';
  cen04.style.display = 'none';
  document.getElementById("s1").className="bt2"
  document.getElementById("s2").className="bt2"
  document.getElementById("s3").className="bt1"
  document.getElementById("s4").className="bt2"
  }
    if(c == "cen04"){
  cen01.style.display = 'none';
  cen02.style.display = 'none';
  cen03.style.display = 'none';
  cen04.style.display = 'block';
  document.getElementById("s1").className="bt2"
  document.getElementById("s2").className="bt2"
  document.getElementById("s3").className="bt2"
  document.getElementById("s4").className="bt1"
  }
}