I Swear English › Modal Verbs › Obligation and Prohibition in the Past
How to form and use the obligation and prohibition in the past
Past Obligations Had To and Past Prohibitions Could Not:
To talk about obligations in the past we use had to. This is because must is only present and future obligations and must have is for logical certainty or speculation about the past.
For example: In the stone age people had to wash in rivers and lakes.
In Roman times people had to pay taxes to Rome and gladiators had to fight in the arena.
Didn't have to talks about something possible but not necessary in the past. It is not a prohibition. We therefore use could not to talk about prohibitions in the past. We can also use was/were not able to, was/were not permitted to, or was/were not allowed to. Notice that couldn't and not able to may also refer to not having an ability in the past.
For example: In Spain before Franco died people couldn't say what they wanted. (prohibition)
Before the law was changed you couldn't visit Britain without a visa. (prohibition)
In Britain after 1930 only women under thirty years of age were not allowed to vote.
Before the hot air baloon was invented people couldn't fly. (no ability in the past)
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This lesson is part of our free English Modal Verbs course. Work through the series in order, or jump to the tense or structure you need next.