The Motivation and Pragmatic Inferences of Non-past-tense Meaning of the English Past Tense

The English past tense has a prototype meaning that something or a state happens in a specific time point of the past.In addition,it also contains the non-past-tense usage which is of non-prototype,such as the present tense and the future tense,which is called hypothetical past and attitudinal past.According to the conceptual metaphor,distance is the conceptual metaphor of the non-past-tense meaning.Distance produces indirectness of using language,which is the motivation of the subjunctive and politeness.