Modals in the present and past

Modals in the present and past

Models are verbs, that we previously explained, which does not change, and they are always come before the main verb in a sentence. However, when changing the main verb tense from present to past, we slightly see some differences:

How to use modals in the present and past


As you can see in these two examples, the main verb “see” becomes “seen” after changing tense from present to past (for examples of irregular verbs click here). Additionally, we can see that the word “have” has been added in the past tense. Therefore, modals in the past can have the following form:

✏️ Modal + have + past participle.

All modal verbs follow the above form except for ones that express obligation, ability and lack of necessity:




Lack of necessity:

Type Modals in the Present Modals in the Past
Obligation You must / have to stop when the traffic lights are red. You had to stop.
Advice You should see a doctor. You should have seen a doctor
Prohibition You mustn't smoke here. You mustn't have smoked there.
Certainty He has a Rolls Royce. He must be very rich.He can't be American. His English is terrible. He must have been rich. He had a big house and an expensive car.He can't have written that poem. He was illiterate.
Permission Can I go out? She could drive her father's car when she was only 15.
Possibility It may / can / could / might rain. It's cloudy. I guess it may / can / could / migh thave been Lacy on the phone.
Lack of necessity You don't have to / needn't buy any tomatoes. There are plenty in the fridge. You didn't have to / didn't need to buy tomatoes.

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