1. The method of acquiring rules for a computer-based expert system, said rules being characterized by conditions involving queries having more than one possible answer, said method comprising, serially receiving portions of a sentence input from an expert, checking said portions as they are received for their confirmation to a predetermined grammar based upon the logical formation of rules for a given subject matter, providing sentence portion selection information to said expert, wherein said selection information is given to the expert by way of feedback in instances where the expert inputs a sentence portion that does not conform to said predetermined grammar, and translating the sentence into the form of a diagnostic rule when the sentence is complete.