9. A method for building concept knowledge in a computer system from a machine-readable dictionary for use by a search engine to facilitate quick and accurate information retrieval, the machine-readable dictionary including a plurality of words in a first language and a plurality of corresponding translated words in a second language, and a plurality of words in the second language and a plurality of corresponding translated words in the first language, said method comprising steps of: providing a seed word in the first language; forward-translating said seed word to obtain a plurality of translated words corresponding to said seed word by looking up said machine-readable dictionary; backward-translating said translated words to obtain a plurality of translated words in the first language corresponding to each of said plurality of translated words obtained by said step of forward-translating respectively, as words of the concept knowledge, by looking up said machine-readable dictionary; storing synonymous words of each translated word in said first language and in said second language; calculating frequency of each translated word in said first language and in said second language; ranking said translated words based on said stored synonymous words and said calculated frequency; presenting said ranked words to a user for allowing the user to select desired words among said ranked words and to delete irrelevant words among said ranked words; and providing the selected desired words to said search engine to perform information retrieval on a knowledge-based level instead of a keyword-based level.
9. A method for building concept knowledge in a computer system from a machine-readable dictionary for use by a search engine to facilitate quick and accurate information retrieval, the machine-readable dictionary including a plurality of words in a first language and a plurality of corresponding translated words in a second language, and a plurality of words in the second language and a plurality of corresponding translated words in the first language, said method comprising steps of: providing a seed word in the first language; forward-translating said seed word to obtain a plurality of translated words corresponding to said seed word by looking up said machine-readable dictionary; backward-translating said translated words to obtain a plurality of translated words in the first language corresponding to each of said plurality of translated words obtained by said step of forward-translating respectively, as words of the concept knowledge, by looking up said machine-readable dictionary; storing synonymous words of each translated word in said first language and in said second language; calculating frequency of each translated word in said first language and in said second language; ranking said translated words based on said stored synonymous words and said calculated frequency; presenting said ranked words to a user for allowing the user to select desired words among said ranked words and to delete irrelevant words among said ranked words; and providing the selected desired words to said search engine to perform information retrieval on a knowledge-based level instead of a keyword-based level. 16. The method for building concept knowledge in a computer system from a machine-readable dictionary for use by a search engine to facilitate quick and accurate information retrieval in accordance with claim 9 , wherein said machine-readable dictionary contains words in more than two languages and corresponding relations thereamong; said method further comprises, after said step of forward-translating, a step of iterating said step of forward-translating with any one language from said more than two languages as the second language and each of the translated words obtained as the seed word respectively, until a predefined number of times is reached, or a predefined number of the translated words are obtained, or all of the translated words in the first language have been translated as seed words.