I am converting a working .NET 4.0 application to .NET 3.5 with string.join
<p>I am converting a working .NET 4.0 application to .NET 3.5. Please, help me
Here is the code:</p>

<pre><code>NameValueCollection qs = new NameValueCollection();
qs["aid"] = "aaa";
qs["fields"] = "1";
qs["aaa"] = "d";

tb.Text = String.Join("&amp;", from item in qs.AllKeys select item + "=" + qs[item]);
</code></pre>
