Forming auxiliary verbs. Whenever you use an auxiliary, check the form of the word that follows.

modal + base form. Use the base form of a verb after can, could, will, would, shall, should, may, might, and must: Alice can read Latin. In many other languages, modals like can or must are followed by the infinitive (to + base form). Do not substitute an infinitive for the base form in English.

perfect have, has, or had + past participle. To form the perfect tenses, use have, has, or had with a past participle: Everyone has gone home. They have been working all day.

progressive be + present participle. A progressive form of the verb is signaled by two elements, a form of the auxiliary be (am, is, are, was, were, be, or been) and the -ing form of the next word: The children are studying. Be sure to include both elements.

Some verbs are rarely used in progressive forms. These are verbs that express unchanging conditions or mental states rather than deliberate actions: believe, belong, hate, know, like, love, need, own, resemble, understand.

passive be + past participle. Use am, is, are, was, were, being, be, or been with a past participle to form the passive voice.

Tagalog is spoken in the Philippines.

Notice that the word following the progressive be (the present participle) ends in -ing, but the word following the passive be (the past participle) never ends in -ing.

If the first auxiliary in a verb phrase is a form of be or have, it must show either present or past tense and must agree with the subject: Meredith has played in an orchestra.