Present Tense I am We are You are You are He/She/It is They are Past Tense I was We were You were You were He/She/It was They were Perfect Form (past participle) I have been, etc. Progressive Form (present participle) I am being, etc. We must choose carefully among these various forms when selecting the proper verb to go with our subject. Singular subjects require singular verbs; plural subjects require plural verbs. That's usually an easy matter. We wouldn't write “The troops was moving to the border.” But some sentences require closer attention. Do we write “The majority of students is (or are) voting against the referendum"? Review carefully the material in our section on Subject-Verb Agreement, and notice how often the choices we make require a familiarity with these forms of the “To be” verb.