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
- Present: you should see my work.
- Past: you should have seen my work.
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:
- Present: I must/have to study hard.
- Past: I had to study hard.
- Present: I can read fast.
- Past: I could read fast.
Lack of necessity:
- Present: you don’t have to pay the bill.
- Past: you didn’t have to pay the bill.
|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.|