Insert variables into interpolated string for XML SOAP request in C#

Question

Hi i'm trying to insert another variable into a string, the ones that comes in the dictionary variable works fine, but i need to insert another upper that section, how can i do it?

    public static string SendRequest(Dictionary<string, string> parameters)

<soap:Body>
    <tem:Section1>
        <tem:token>
            **INSERT ANOTHER VARIABLE HERE**
        </tem:token>
        <tem:Section2>
            <{0} xmlns=""{1}"">{2}</{0}>
         </tem:Section2>
    </tem:Section1>
</soap:Body>

string parms = string.Join(string.Empty, parameters.Select(kv => String.Format("<{0}>{1}</{0}>", kv.Key, kv.Value)).ToArray());