//万能选项卡

function PaPtabs(thisObj, num) {

  if (thisObj.className == "active") return;

  var tabObj = thisObj.parentNode.id;

  var tabList = document.getElementById(tabObj).getElementsByTagName("li");

  for (i = 0; i < tabList.length; i++) {

    if (i == num) {

      thisObj.className = "active";

      document.getElementById(tabObj + "C" + i).style.display = "block";

    }

    else {

      tabList[i].className = "pnormal";

      document.getElementById(tabObj + "C" + i).style.display = "none";

    }

  }

};

<div class="Hotitle MT15">

        <h4>肿瘤热门</h4>

        <ul id="N3">

            <li class="active" onclick="PaPtabs(this,0);">1111</li>

            <li onclick="PaPtabs(this,1);">22222</li>

        </ul>

    </div>

    <div class="Rask ImgWod" id="N3C0">

      aaaa

    </div>

    <div class="Rask ImgWod none" id="N3C1">

      bbbb

    </div>