Modal verbs: Possibility/Certainty/Obligation/Necessity

Well, even though it was a bad start, it must have been destiny!

• express certainty about the present

• express certainty about the past

• talk about a possibility in the past

I should have listened to my mother´s suggestion.

• express certainty about the present

• criticise past behaviour

• describe a past lack of obligation/necessity

If I had gotten up early, I could have been on time.

• describe past ability

• talk about a future possibility

• talk about a possibility in the past

She didn´t have to go, but she insisted.

• criticise past behavior

• describe a past lack of obligation/necessity

• talk about future possibility

You should had offered your seat to the pregnant woman.

• talk about a possibility in the past

• describe a past lack of obligation/necessity

• talk about a present obligation/necessity

When I was younger I could run very fast.

• criticise past behaviour

• decribe past ability

• express certainty about the past

It could have been a good weekend if we had stayed at home.

• talk about a possibility in the past

• talk about a future possibility

• criticise past behaviour

It must have been a very good period to live in.

• express certainty about the past

• express certainty about the present

• describe past ability