Which form indicates the past tense for the verb 'to be' for all persons?

The identification of 'were' as the past tense form of the verb 'to be' for all persons is accurate because it applies to the second person singular and plural (you), and to all forms of the plural (we, they). In English grammar, 'were' functions as the past tense of 'to be' used with these subject pronouns.

In contrast, the other options are not indicative of the past tense for all persons. 'Be' is the base form of the verb and does not express any tense. 'Is' is the present tense form used specifically with third-person singular subjects (he, she, it). 'Being' is the present participle form, often used in continuous tenses or passive voice structures, but it does not convey a past tense either. Thus, 'were' serves uniquely to encapsulate the past tense across various subjects, making it the correct choice.