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.
- We may ask him a few questions.
- I can manage a motor car.
- You must inquire the way.
- He might give you a chance.
- I could show you his house if you would permit me.
- 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.
288. Potential phrases may be arranged in tables of conjugation, like that on [pp. 108–110]. They are often called, collectively, the potential mood.
| Present Tense | |
|---|---|
| SINGULAR | PLURAL |
| 1. I may strike.[34] | 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.[35] | 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. |
| 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. |
289. Can (past tense, could) regularly indicates that the subject is able to do something.
- John can ride a bicycle.
- Harry could swim.
290. May (past tense, might) indicates (1) permission, (2) possibility or doubtful intention, (3) a wish.
- (1) You may borrow my pencil.
- I told him that he might join our party.
- (2) He may accept my offer.
- You might not like it.
- (3) May good fortune attend you!