Modal Verbs and Time of the Action or State
Be careful not to confuse verb tenses and the time of an action or state. A verb tense is the form of the verb used to express the relative time an action or state takes place.
For example, should is the past tense of shall. Analyze the different times it expresses in the following sentences:
1. We should leave now.
2. We should leave at 2 tomorrow.
3. We should have left an hour ago.
In the above sentences, should expresses advisability. Although it is the past tense, it expresses advisability in the present, future, and past in Sentences 1, 2, and 3.
Sentence 3 also shows an interesting characteristic of modal verbs in that they can be used to express a modality in a particular time frame while the main verb can be in a different time frame. In other words, should itself expresses advisability in the present, but the action itself (leaving) is in the past.
Modals and main verbs in different time frames
- You have been working for 10 hours now. You must be tired.
- You worked for 10 hours yesterday. You must have been tired.
In the above sentences, must expresses the idea of a logical conclusion.
In Sentence A, both the modal and the main verb express an idea in the present. (The present conclusion is about something that is happening now.)
In Sentence B, the conclusion is in the present, but the state expressed by the main verb is in the past. (I conclude now that you were tired in the past.)
- John may come to the party (if he wants).
- John may come to the party tomorrow (I’m not sure).
- John may have come to the party yesterday (I did not see him there).
The modal verb may is in the present tense. It expresses permission in Sentence C but a possibility or likelihood in the other sentences.
In Sentence C, both the permission and the action (coming to the party) are a statement of fact (present).
In Sentence D, the possibility is in the present and refers to an action in the future.
In Sentence E, the possibility is in the present (I think now that it is possible), and the action is in the past (maybe he came to the party yesterday).
Present and Past Forms of Modal Verbs
Some modal verbs have both present and past forms. As noted in the above section, some of these forms also express different time frames depending on how they are used.
Here are modal verbs in their present and past forms, respectively:
are able to were able to
have to had to
must had to
ought to —
The following modal and semi-modal verbs can be conjugated in all verb tenses: be able to, dare, have to, and need.
Modal Verbs and their Meanings
Continue the lesson for lists of modal verbs and their meanings.