Thanks a lot! So does Wolfram Alpha has such kind of data source that can answer " what are the stores that sell iphone 6", it seems that it is not computational based query, however, if Wolfram Alpha has stored such kind of data and then it may answer this query. The reason I am interested in such kind of stuff is that I think we can use the same technology that Wolfram Alpha uses to improve our search engineer, namely, to achieve our dream ---- one query, one answer (rather than a list of website which agrees on some keywords but are not related in terms of its content). And ever more, one query one answer that includes all aspects about the query, which is just what Wolfram Alpha does now! I am really interested in how Wolfram Alpha can achieve this and how it can understand human's language (query), as I understand Natural Language Processing has not achieved this ultimate goal by now. I wish that in the future after I type " what can I do if my baby is crying all the time" and then get the answer from a doctor or phychologist which is scientific.