9. One or more tangible computer-readable storage media having computer-executable instructions stored thereon that are configured to program one or more computing devices to perform operations comprising: receiving an inquiry word; segmenting the inquiry word into one or more keywords; searching an inverted index of a group of documents to determine in the group one or more documents in which one or more of the keywords are matched; and searching a forward index of a respective document of the determined one or more documents to generate an abstract for the respective document, the searching including: determining a length limit of the abstract; identifying a plurality of portions within the respective document, each portion of the plurality of portions including a respective beginning position in the respective document and a respective ending position in the respective document, the identifying including identifying, within the respective document, every portion that is within the length limit by traversing the forward index character-by-character or word-by-word; finding a portion among the plurality of portions, the portion including a highest number of the one or more keywords between a beginning position and an ending position compared with any other portion of the plurality of portions; and selecting the found portion to be the abstract of the respective document.
10. The one or more tangible computer-readable storage media of claim 9 , wherein the identifying the plurality of portions within the respective document comprises: traversing, by the computing device, at least one word in the forward index of the respective document; recording, by the computing device, the at least one traversed word and a location of the at least one traversed word in a first data structure by using the location of the traversed word as an index of the first data structure; and when the at least one traversed word matches one of the keywords, recording, by the computing device, the at least one traversed word and the location of the at least one traversed word in a second data structure by using the at least one traversed word as an index of the second data structure.