27. The method according to claim 26 , wherein the lost content searching step of retrieving the service mapping rule meeting the following conditions as a matched service mapping rule from the service mapping rule base: a requirement in the service mapping rule is identical to a requirement of the semantically-analyzed query; and a service parameter in the service mapping rule contains a parameter of the semantically-analyzed query.
26. A method of selecting service based on an incomplete query, comprising: a semantic analyzing step, performed by at least one processor, of analyzing an incomplete query from a user semantically; a service selecting step, performed by the at least one processor, of complementing the incomplete query based on a semantically-analyzed query to complete the incomplete query, and selecting a corresponding selected service from among a plurality of services based on a complete query; and a retrieving step, performed by the at least one processor, of retrieving an answer according to the corresponding selected service, wherein the service selecting step comprises an automatic service selecting step of searching lost content in a current query by using a service mapping rule base and complementing the lost content through searching a fact base, wherein the automatic service selecting step comprises: a lost content searching step of matching the semantically-analyzed query with a service mapping rule in the service mapping rule base, and extracting a service type to which the incomplete query belongs and a lost parameter in the incomplete query; a fact matching step of matching the semantically-analyzed query with a fact in a fact base to find a matched fact, and extracting a fault value from the matched fact as a lost parameter value; and a query complementing step of adding the service type, the lost parameter and the lost parameter value into the semantically-analyzed query to form the complete query.