The English Query processor remembers the questions that have been recently asked. If you use pronouns to refer to information that you are examining, it remembers the previous results and uses those to interpret follow-up questions. For example, suppose that you start off with this query:
Who rented movies in the last 30 days?
Using this list as a starting point, you can then ask questions that relate only to the data returned by these follow-up queries:
How many were Science Fiction?
Of those, which movies were directed by Stanley Kubrick?
Which of those had a running time over two hours?