Is knitting quiet hobby? (общий)
Is knitting quiet or noisy hobby? (альт.)
knitting is quiet hobby, isn't it? (разд)
What is quiet hobby? (к подлежащему)
What hobby is knitting? (спец)
Are they interested in sightseeing?
Are they interested in sightseeing or in travelling?
they are interested in sightseeing, aren't they?
Who is interested in sightseeing?
What are they interested in?