as a modal verb phrase, 'used to' expresses a past habit or a state that was true in the past but is no longer the case in the present.
'used to' is followed by the base form of a verb. It is not used to describe a single event that happened in the past, but rather a recurring action or a state that persisted over a period of time.
I used to play football every weekend, but now I don't have the time.
She used to live in New York before she moved to Los Angeles.
We used to go to that café all the time when we were students.
a common mistake is to use 'used to' in the present tense, which is incorrect. For example, 'I use to go to the gym' should be 'I used to go to the gym.'
The negative form is 'didn't use to' (e.g., 'I didn't use to like coffee, but now I love it'). Questions are formed like 'Did you use to play basketball?'