We use used to + infinitive or would + infinitive to describe repeated actions in the past:
I used to keep the windows closed when I first moved in. (but I stopped doing this)
I would leave the windows open whenever I was at home.
Note: we do not usually use would in the negative form and in Yes/No questions.
- We use used to + infinitive to describe past states that are usually no longer true:
We used to live in London when I was a kid. (but we don’t now: not
We would live in London when I was a kid.)
We do not use used to to refer to specific restricted periods in the past or saying how long it took or how many times:
I lived in New York City for ten years. (not
I used to live in New York City for ten years.)
I went to London twice when I was young. (not
I used to go to London twice when I was young.)
Note: we do not use would with state verbs.