Which form of the verb "to be" is used as the second person singular past?

The second person singular past form of the verb "to be" is "were." This is particularly noteworthy because in English, the verb "to be" changes depending on the subject and the tense. In the past tense, "were" is correctly used for the second person singular (you), as in "You were there." This usage is distinct from the present tense forms such as "are" for the second person singular present ("You are"), or "is," which applies to the third person singular present ("He/She/It is"). The option "be" corresponds to the base form of the verb and does not specify tense or the subject pronoun. Thus, "were" is the appropriate choice for this question.