This document discusses basic tenses in English sentences. It explains the structure of present and past simple sentences, noting that the subject is followed by a form of "to be" or the verb. For present tense, this includes is, am, are followed by the verb or a verb with an -s ending. For past tense, it uses was, were followed by the verb or a verb ending in -ed, along with did not for negatives and interrogatives. An important note is provided that "be" and a verb should not be used together in simple tenses.