LEC 4 1. Truth-Functionality Propositional logic 的connectives（连接词）are truth-functional 但是，有时候的描述不是true-functional的，比如："Knowing that", "It is necessary that","it is oblligatory that", "It is always

LEC 4 1. Truth-Functionality Propositional logic 的connectives（连接词）are truth-functional 但是，有时候的描述不是true-functional的，比如："Knowing that", "It is necessary that","it is oblligatory that", "It is always