It is always a very good advantage to speak the local language but if you don't, please don't just say "no" or "no but I am ready to learn", answer in a positive way like "Well, I can't keep a discussion but since I know I had this interview I've started to learn a bit about and I bought a book to learn it" Try to say a few words or to tell them that you will work on that in the local laguage. It is always appreciated! The best example is when you see tourists talking to you in your language. Don't you like it?!