.Net 3.0 library and System.Speech

Hello
I heard the unity does not support .net 3.0 libraries.
can i use .net 3.0 compiled dll in .net 2.0. and the make a dll for unity?

I need some speech recognition functionality in my application, for that i am using System.Speech.Recognition, but problem is that it is compiled with .net 3.0.

Now if i make 2.0 dll and use it with unity, it does not show any error but it does not throw any events for speech recognition.

Please help