Obligation and Prohibition in the Past. Had to and Couldn't. Modals 204
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)
The following video explains Obligation and Prohibition in the Past:
Obligation in the past. Now must is present and future. Therefore to talk about an obligation in the past, you have to use had to. So, when I was a boy, I had to get up early. I had to clean my room. OK. These are obligations in the past. Now the problem comes with prohibitions in the past, because if you remember, I don't have to is not the same as I mustn't. I don't have to, it's... it's not necessary to. So for example when I was a boy I didn't have to pay for my school. It wasn't necessary in the past. But how do we make a prohibition? To make a prohibition we have to say I couldn't. I couldn't stay out late. Or you could use, I was not allowed to. Or I was not permitted to. I like couldn't because couldn't is another modal verb. So, obligation, or prohibition in the past: I couldn't. OK. So, when I was a boy I had to make my bed every day. OK. But I couldn't smoke. OK. Smoking was prohibited. Erm... I didn't have to clean the bathroom every day. It wasn't necessary, but I could if I wanted. OK. So, obligation and prohibition in the past. Thanks for watching and I'll see you in another video. Bye for now.