1. Is he looking for the book which he lost?    What Is he looking for ? 
    He isn't looking for the book which he lost.
2. Are all the birds  flying south?   Where are all the birds flying?
    All the birds are not flying south.
3. Is the sky getting very dark?  What is getting very dark?
    The sky isn't getting very dark.
4.  Are they laughing at what you said?  What are they laughing at?
    They aren't laughing at what you said.
5. Are they travelling in Europe at present?  Where are they travelling at     present?                   They aren't travelling in Europe at present.   
6. Is Helen taking dancing lessons at the country club?  
    Where is Helen taking dancing lessons?                                                     Helen isn't taking dancing lessons at the country club.
7. Is  Mr. Evans  writing a series of articles on the economic situation?
     What is Mr. Evans  writing?
     Mr. Evans isn't  writing a series of articles on the economic situation.
8.  Is Ann  doing well in her studies at present?
      How well is Ann doing in her studies at present?
      Ann isn't doing well in her studies at present.