Use of Modal Auxiliaries

Use of Modal Auxiliaries :


Several auxiliary verbs are used to form verb-phrases indicating ability, possibility, obligation or necessity.

Such verb-phrases are called potential phrases, that is phrases of possibility.

The auxiliary verbs used in potential phrases are may, can, must, might, could, would and should. They are called modal auxiliaries and are followed by the infinitive without TO.

1. We may ask him a few questions.
2. I can manage a motor car.
3. You must inquire the way.
4. He might give you a chance.
5. I could show you his house if you would permit me.
6. I should enjoy a sea-voyage.

Note : The fact that give, etc., in such phrases as can give, are infinitives may be seen by comparing “I can strike” with “I am able to strike,” “I may strike” with “I am permitted to strike,” “I must strike” with “I am obliged to strike,” and so on. In earlier periods of the language, when the infinitive had a special ending (-an or -en), the nature of the construction was unmistakable.



Potential phrases may be arranged in tables of conjugation. They are often called, collectively, the potential mood.

Active Voice

Present Tense

SINGULAR PLURAL

1. I may strike. 1. We may strike.
2. Thou mayst strike. 2. You may strike.
3. He may strike. 3. They may strike.

Past Tense

1. I might strike. 1. We might strike.
2. Thou mightst strike. 2. You might strike.
3. He might strike. 3. They might strike.

Perfect (or Present Perfect) Tense

1. I may have struck.36 1. We may have struck.
2. Thou mayst have struck. 2. You may have struck.
3. He may have struck. 3. They may have struck.

Pluperfect (or Past Perfect) Tense

1. I might have struck.37 1. We might have struck.
2. Thou mightst have struck. 2. You might have struck.
3. He might have struck. 3. They might have struck.

Passive Voice

Present Tense

I may be struck, etc. We may be struck, etc.

Past Tense

I might be struck, etc. We might be struck, etc.

Perfect (or Present Perfect) Tense

I may have been struck, etc. We may have been struck, etc.

Pluperfect (or Past Perfect) Tense

I might have been struck, etc. We might have been struck, etc.



Can (past tense, could) regularly indicates that the subject is able to do something.

1. John can ride a bicycle.
2. Harry could swim.



May (past tense - might) indicates (1) permission, (2) possibility or doubtful intention (3) a wish.

1. You may borrow my pencil.
2. I told him that he might join our party.
3. He may accept my offer.
4. You might not like it.
5. May good fortune attend you!



In asking permission, the proper form is “May I?” not “Can I?” With negatives, however, can is more common than may, except in questions. Thus…..

Question : May I (or mayn’t I) play ball this morning?

Answer : No, you cannot; but you may play this afternoon.



Must expresses necessity or obligation.

1. We must all die sometime.
2. You must wait for the train.
3. You must not be discouraged by failure.

Note : Must, though originally a past tense, is in modern English almost always used as a present. Past necessity may be expressed by had to with the infinitive such as….I had to wait for the train.



Ought with the present infinitive, expresses a present duty or moral obligation; with the perfect infinitive, a past duty or obligation. Should is often used in the same sense.

1. I ought to write that letter. [Present.]
2. You ought not to object. [Present.]
3. This roof ought to be mended. [Present.]
4. I ought to have known better. [Past.]
5. Your dog ought not to have been unleashed. [Past.]
6. You should be careful. [Present.]
7. The garden should have been weeded yesterday. [Past.]

Note : Ought is really an old past tense of the verb owe, but is now always a present. Its former meaning may be seen in Dame Quickly’s “You ought him a thousand pound” (Shakespeare, 1 Henry IV, iii. 3. 152).

1. Had should never be prefixed to ought. Correct……Incorrect

You ought to stay at home…….You had ought to stay at home.

We oughtn’t to make so much noise. ……..We hadn’t ought to make so much noise.

John ought to begin, oughtn’t he?........John ought to begin, hadn’t he?



Should and ought sometimes express what would certainly be expected in the case supposed.

2. Three weeks {should | ought to} suffice.
3. If the train is on time, he {should | ought to} arrive at six.
Would in all three persons sometimes indicates habitual action in the past.

1. I would gaze at the sea for hours at a time.

2. Whenever we asked Edward about his adventures, he would begin to talk of something else.

Use of Modal Auxiliaries :

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