19. 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 current user query history 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 current query belongs and a lost parameter in the current query; a latest query detecting step of searching a latest query contained the lost parameter in the current query from the current user query history base, and extracting the parameter value corresponding to the lost parameter in the current query; and a query complementing step of adding the service type, the lost parameter and the parameter value into the semantically-analyzed query to form the complete query.
19. 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 current user query history 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 current query belongs and a lost parameter in the current query; a latest query detecting step of searching a latest query contained the lost parameter in the current query from the current user query history base, and extracting the parameter value corresponding to the lost parameter in the current query; and a query complementing step of adding the service type, the lost parameter and the parameter value into the semantically-analyzed query to form the complete query. 22. The method according to claim 19 , wherein the lost content searching step comprises a 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 semantically-analyzed query.