Modals in the past and present

Modals in the present 
and past

Modals are verbs that do not change, and they always come before the main verb in a sentence. However, when changing the main verb tense from present to past, we see some slight 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. However, you should pay attention to irregular verbs (learn more about irregular verbs). Additionally, we can note that the word “have” has been added in the past tense. Therefore, modals in the past have the following form:

✏️ Modal + have + past participle.

All modal verbs follow the above form except the 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 big house and an expensive car. He must be very rich. He must have been rich. He had a big house and an expensive car.
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 / might have 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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