Complete the following sentence with a (compound) word derived from the one(s) given in bracket.
More than any other single ( ), writing has transformed human consciousness.(invent)
假定在产品A和产品B之间有以下关系:QA=80PB-0.5 。式中,QA为消费者对产品A的需求量;PB为产品B的价格。 试求:(1)