Another auxiliary-type usage of the copula in English is together with the "to"-infinitive to denote an obligatory action or expected occurrence: "I am to serve you;" "The manager is to resign." It can be put also into past tense: "We were to leave at 9." For forms like "if I was/were to come," see English conditional sentences. (Note that by certain criteria, the English copula "be" may always be considered an auxiliary verb; see Diagnostics for identifying auxiliary verbs in English.)