For business related software developing, it is very difficult to make a clear Specification document. For purchaser, it may be impossible to describe their requirements clearly and completely. For supplier, it must be very hard to help their purchaser describing their requirements. Unfortunately there is no way to identify purchaser’s requirement logically and formally. In order to overcome this difficulty, it is necessary to improve communication ability to laddering the stairs of abstraction and to educate techniques for creating logical and technical sentences.