21. A computer implemented method of providing a natural language answer to a natural language question, the method comprising: receiving, over a computer network, a query comprising a grammatical question; submitting the query to a lookup engine; receiving initial search results from the lookup engine, the initial search results comprising a plurality of documents, wherein the initial search results comprise a ranking of the plurality of documents according to relevance; identifying, in the plurality of documents, a plurality of candidate sentences; calculating a frequency of a plurality of n-grams appearing in the plurality of candidate sentences, wherein n ranges at least from 1 to 2; assigning, to each candidate sentence, a score, wherein the score comprises (1) the frequency of a plurality of n-grams appearing in the candidate sentence, and (2) a rank of the candidate sentence according to the ranking of the plurality of documents; sorting the candidate sentences according to score, whereby a rating of candidate sentences is produced; and sending, over a computer network, a reply to the query, the reply comprising at least a top candidate sentence from the rating of candidate sentences.
21. A computer implemented method of providing a natural language answer to a natural language question, the method comprising: receiving, over a computer network, a query comprising a grammatical question; submitting the query to a lookup engine; receiving initial search results from the lookup engine, the initial search results comprising a plurality of documents, wherein the initial search results comprise a ranking of the plurality of documents according to relevance; identifying, in the plurality of documents, a plurality of candidate sentences; calculating a frequency of a plurality of n-grams appearing in the plurality of candidate sentences, wherein n ranges at least from 1 to 2; assigning, to each candidate sentence, a score, wherein the score comprises (1) the frequency of a plurality of n-grams appearing in the candidate sentence, and (2) a rank of the candidate sentence according to the ranking of the plurality of documents; sorting the candidate sentences according to score, whereby a rating of candidate sentences is produced; and sending, over a computer network, a reply to the query, the reply comprising at least a top candidate sentence from the rating of candidate sentences. 27. The method of claim 21 , wherein the reply comprises candidate sentences whose scores meet a predetermined threshold.