22. The tangible computer-readable storage device of claim 20 , wherein the operations further comprise determining a query relevance score for one or more of the returned search results, and wherein the score for one or more of the candidate topic-answer pairs is further based on the query relevance scores of one or more of the search results that reference an annotated resource in which the candidate topic occurs.
20. A tangible computer-readable storage device having instructions stored thereon that, when executed by one or more computer processors, cause the processors to perform operations comprising: identifying one or more candidate topics from a query; generating, for each candidate topic, a candidate topic-answer pair that includes (i) the candidate topic, and (ii) an answer to the query for the candidate topic; obtaining search results based on the query, wherein one or more of the search results references an annotated resource, wherein an annotated resource is a resource that, based on an automated evaluation of the content of the resource, is associated with an annotation that identifies one or more likely topics associated with the resource; for each candidate topic-answer pair, determining a score for the candidate topic-answer pair based on (i) an occurrence of the candidate topic in the annotations of the resources referenced by one or more of the search results, and (ii) an occurrence of the answer in annotations of the resources referenced by the one or more search results, or in the resources referenced by the one or more search results; and determining whether to respond to the query with one or more answers from the candidate topic-answer pairs, based on the scores.