The subjunctive mood called "were-subjunctive" in were-subjunctive English expresses fictional assumptions that are contrary to the actual situation by distorting the tense form. The specific method is to "backwards" the tense form. "A tense". This expression may not be accurate, but it is very practical and easy to understand. The specific method is to change the present tense into the past tense, and change the past tense into "past past". In In this use of the subjunctive mood, the verb be must go back at least one tense to become the "past tense" were (was, is, am, and are are generally not used in the subjunctive mood, and it will be written as were after going back one tense). Therefore, this kind of subjunctive mood that expresses fictitious assumptions that is contrary to the actual situation is called the "were" subjunctive mood.