onMouseOver="MM_showHideLayers('D2','','show');MM_showHideLayers('D1','','hide')"
<table height="200" width="200" border=1> <tr height=20> <td onMouseOver="showContent('trAA','trBB')">aa</td><td onMouseOver="showContent('trBB','trAA')">bb</td> </tr> <tr id="trAA"> <td colspan="2"> <table width="100%" height="100%"> <tr><td>aa的內容</td></tr> </table> </td> </tr> <tr id="trBB" style="display:none"> <td colspan="2"> <table width="100%" height="100%"> <tr><td>bb的內容</td></tr> </table> </td> </tr> </table> <table border=1><tr><td>下面的內容</td></tr></table>