14. The system of claim 13, wherein the selectively extracting means extracts each section of the second language document which contains a corresponding word of each first language character string according the first and second language correspondence dictionary, and selectively extracts each corresponding second language character string according to a level of correspondence between a section of the first language document from which each first language character string is extracted and each section of the corresponding second language document to which each corresponding second language character string belongs.
14. The system of claim 13, wherein the selectively extracting means extracts each section of the second language document which contains a corresponding word of each first language character string according the first and second language correspondence dictionary, and selectively extracts each corresponding second language character string according to a level of correspondence between a section of the first language document from which each first language character string is extracted and each section of the corresponding second language document to which each corresponding second language character string belongs. 16. The system of claim 14, wherein the selectively extracting means extracts each corresponding second language character string from each section of the corresponding second language document which has corresponding words for constituent words of each first language character string which are arranged in an identical manner as the constituent words of each first language character string are arranged in the first language.