They have just read this book.
Have they just read this book?
They have just read this book, haven't they?
Have they just read this book or this article?
Who has just read this book?
What have they just read?
They have been watching this film for two hours.
Have they been watching this film for two hours?
They have been watching this film for two hours, haven't they?
Have they been watching this film or cartoon for two hours?
Who has been watching this film for two hours?
How long have you been watching this film?