13. A storage medium storing computer executable instructions that when executed by a processor instruct the processor to: receive a first query comprising a plurality of words; acquire a session identifier (ID) corresponding to the first query; acquire, according to the session ID, a second query that belongs to a same session as the first query; determine that the first query and the second query forms a query chain, wherein the second query meets at least one of the following conditions to form the query chain with the first query: a length of a longest common clause of the first query and the second query is greater than a first threshold; or a minimum quantity of operations required for converting the first query into the second query is less than a second threshold; or the first query is mapped to a first vector, the second query is mapped to a second vector, and an included angle or a distance between the first vector and the second vector is less than a third threshold; and based on the determination: acquire a change-based feature of each word in the first query relative to the second query; and identify a stop word in the first query according to the change-based feature of said each word in the first query relative to the second query.
13. A storage medium storing computer executable instructions that when executed by a processor instruct the processor to: receive a first query comprising a plurality of words; acquire a session identifier (ID) corresponding to the first query; acquire, according to the session ID, a second query that belongs to a same session as the first query; determine that the first query and the second query forms a query chain, wherein the second query meets at least one of the following conditions to form the query chain with the first query: a length of a longest common clause of the first query and the second query is greater than a first threshold; or a minimum quantity of operations required for converting the first query into the second query is less than a second threshold; or the first query is mapped to a first vector, the second query is mapped to a second vector, and an included angle or a distance between the first vector and the second vector is less than a third threshold; and based on the determination: acquire a change-based feature of each word in the first query relative to the second query; and identify a stop word in the first query according to the change-based feature of said each word in the first query relative to the second query. 15. The storage medium according to claim 13 , wherein the processor is instructed to: query a word feature database of the information retrieval system according to said each word in the first query; and acquire a statistical feature of said each word in the first query; and identify the stop word in the first query according to the statistical feature of said each word in the first query and the change-based feature of said each word in the first query relative to the second query.