1. I don't know
   1. I have no/any
      1. clue - ipucu
      2. hint - ipucu
      3. idea - fikir
      4. on what you are talking about
   2. I'am sorry but I can't help you here
   3. You know, I have been wondering that, too
      1. Present Perfect Cont.
         1. I have been waiting you
         2. I have been working in this company for 5 years
         3. She has been working here since morning
      2. Present Perfect
         1. I have eaten
         2. I have painted
2. No opinion
   1. I have never given it much thought
      1. never nothing no-one nobody nowhere neither
         1. I never smoke
         2. She loves nothing
         3. I know nobody here
         4. We will travel nowhere this year
         5. I want neither
3. give me a clue! There is no clues