These rules encode a substantial amount of linguistic knowledge about the long distance dependencies prevalent in questions, which would be challenging to learn from existing corpora of questions and answers consisting typically of only thousands of examples (e.g., Voorhees, 2003).
the following sequence of transfor-During the Gold Rush years in northern California, Los Angeles became known as the "Queen of the Cow Counties" for its role in supplying beef and other foodstuffs to hungry miners in the north.