et us
consider what the constructor's parameters would have to be in
order to allow &quot;pair&quot; to hold non-reference types,
references, and constant references:</p>

<table border="1" cellpadding="7" cellspacing="1" width="638">
    <tr>
        <td valign="top" width="50%">Type of &quot;T1&quot;</td>
        <td valign="top" width="50%">Type of parameter to
        initializing constructor</td>
    </tr>
    <tr>
        <td valign="top" width="50%"><pre>T</pre>
        </td>
        <td valign="top"