2: Who is the story 'The Hobbit' written by?
3: The Loch Ness Monster not been seen much since that time. / The Loch Ness Monster has been seen by few since then.
4: A new restaurant has been opened in the city by a famous chef.
5: Used books are not sold here. / Used books are not sold here at the moment.
6: Were other students asked to play by the sports teacher?
They might not be exactly correct, but this is a version of it.