59a Form verb phrases appropriately.
Verb phrases can be built up out of a main verb and one or more helping (auxiliary) verbs (32b).
Immigration figures rise every year.
Immigration figures are rising every year.
Immigration figures have risen every year.
Immigration figures have been rising every year.
Verb phrases have strict rules of order. If you try to rearrange the words in any of these sentences, you will find that most alternatives are impossible. You cannot say Immigration figures rising are every year or Immigration figures been have rising every year. The only permissible change to word order is to form a question, moving the first helping verb to the beginning of the sentence: Have immigration figures been rising every year?
Putting helping verbs in order
In the sentence Immigration figures may have been rising, the main verb rising follows three helping verbs: may, have, and been. Together these helping and main verbs make up a verb phrase.
- May is a modal (59b) that indicates possibility; it is followed by the base form of a verb.
- Have is an auxiliary verb (32b) that in this case indicates the perfect tense (32e); it must be followed by a past participle (been).
- Any form of be, when it is followed by a present participle ending in -ing (such as rising), indicates the progressive tense (32e).
- Be followed by a past participle, as in New immigration policies have been passed in recent years, indicates the passive voice (32g).
As shown in the chart below, when two or more auxiliaries appear in a verb phrase, they must follow a particular order based on the type of auxiliary: (1) modal, (2) a form of have used to indicate a perfect tense, (3) a form of be used to indicate a progressive tense, and (4) a form of be used to indicate the passive voice. (Very few sentences include all four kinds of auxiliaries.)
Only one modal is permitted in a verb phrase.
Forming helping verbs
Whenever you use a helping verb, check the form of the word that follows. The guidelines that follow describe the appropriate forms.
| Modal | Perfect Have | Progressive Be | Passive Be | Main Verb | ||
|---|---|---|---|---|---|---|
| Sonia | — | has | — | been | invited | to visit a family in Prague. |
| She | should | — | — | be | finished | with school soon. |
| The invitation | must | have | — | been | sent | in the spring. |
| She | — | has | been | — | studying | Czech. |
| She | may | — | be | — | feeling | nervous. |
| She | might | have | been | — | expecting | to travel elsewhere. |
| The trip | will | have | been | being | planned | for a month by the time she leaves. |
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.
Sanjay should have studied for the test.
They must be going to a fine school.
In many other languages, modals such as can and must are followed by an infinitive (to + base form). In English, only the base form follows a modal.
Alice can 
read Latin.
Notice that a modal auxiliary can express tense (for example, can or could), but it never changes form to agree with the subject.
PERFECT HAVE + 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 a verb is signaled by two elements, a form of the helping verb be (am, is, are, was, were, be, or been) and the -ing form of the next word: The children are studying.
Some verbs are rarely used in progressive forms. These verbs 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 with the progressive be the following word (the present participle) ends in -ing, but with the passive be the following word (the past participle) never ends in -ing.
Takeo is studying music.
Natasha was taught by a famous violinist.
If the first helping verb in a verb phrase is be or have, it must show either present or past tense, and it must agree with the subject: Meredith has played in an orchestra or Meredith had played in an orchestra before she joined the band.