[解決済み] Bootstrapのカラムを複数行にまたがるようにするにはどうすればよいですか？

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet"/>


<div class="row">
    <div class="col-md-4">
        <div class="well">1
            <br/>
            <br/>
            <br/>
            <br/>
            <br/>
        </div>
    </div>
    <div class="col-md-8">
        <div class="row">
            <div class="col-md-6">
                <div class="well">2</div>
            </div>
            <div class="col-md-6">
                <div class="well">3</div>
            </div>
        </div>
        <div class="row">
            <div class="col-md-6">
                <div class="well">4</div>
            </div>
            <div class="col-md-6">
                <div class="well">5</div>
            </div>
        </div>
    </div>
</div>
<div class="row">
    <div class="col-md-4">
        <div class="well">6</div>
    </div>
    <div class="col-md-4">
        <div class="well">7</div>
    </div>
    <div class="col-md-4">
        <div class="well">8</div>
    </div>
</div>

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/2.3.2/css/bootstrap.min.css" rel="stylesheet"/>

<div class="row-fluid">
    <div class="span4"><div class="well">1<br/><br/><br/><br/><br/></div></div>
    <div class="span8">
        <div class="row-fluid">
            <div class="span6"><div class="well">2</div></div>
            <div class="span6"><div class="well">3</div></div>
        </div>
        <div class="row-fluid">
            <div class="span6"><div class="well">4</div></div>
            <div class="span6"><div class="well">5</div></div>
        </div>
    </div>
</div>
<div class="row-fluid">
    <div class="span4">
        <div class="well">6</div>
    </div>
    <div class="span4">
        <div class="well">7</div>
    </div>
    <div class="span4">
        <div class="well">8</div>
    </div>
</div>