C# join with normal and final delimiters

public static string JoinString(IEnumerable<string> elements, string delimiter = ", ", string finalDelimiter = " or ", string emptyEnumerator = "") {
    using (IEnumerator<string> enumerator = elements.GetEnumerator()) {
        return JoinString(enumerator, delimiter, finalDelimiter, emptyEnumerator);
    }
}
public static string JoinString(IEnumerator<string> elements, string delimiter = ", ", string finalDelimiter = " or ", string emptyEnumerator = "") {
    if (!elements.MoveNext()) {
        return emptyEnumerator;
    }
    StringBuilder sb = new StringBuilder();
    sb.Append(elements.Current);
    if (elements.MoveNext()) {
        string last = elements.Current;
        while (elements.MoveNext()) {
            sb.Append(delimiter).Append(last);
            last = elements.Current;
        }
        sb.Append(finalDelimiter).Append(last);
    }
    return sb.ToString();
}