This tense is used for three purposes.

One is to represent a habit or a regular activity in the past.

Active Voice

The structure in such a case is “subject used to v1 object.”

I used to play cricket. Did I use to play cricket? (Did Use, Not Did Used)

I did not use to play cricket. Did I not use to play cricket?

I didn’t use to play cricket. Didn’t I use to play cricket?

Passive Voice

The structure in such a case is “subject used to be v3 by object.”

Vegetables used to be cut by me. Did vegetables use to be cut by me?

You did not use to be taught by me. Did you not use to be taught by me?

You didn’t use to be taught by me. Didn’t you use to be taught by me?

On a side note, if you want to refer to your usual reaction to something in the past, you use “would.”

You served it nicely. I would be pleased.

Also, it is used to refer to something you did at a point.

The syntaxes in this case are the following.

Active Voice

subject v2 object

I ate food. Did I eat food?

I did not eat food. Did I not eat food?

I didn’t eat food. Didn’t I eat food?

Remember “Did V1.”

Passive Voice

subject was/were v3 by object

Was Singular Nouns

Were Plural Nouns

I He She It Was We You They Were

Food was eaten by me. Was food eaten by me?

Food was not eaten by me. Was food not eaten by me?

Food wasn’t eaten by me. Wasn’t food eaten by me?

Qualities held in the past are also represented using this tense.

Subject was/were (article) adjective/noun

I was a teacher. Was I a teacher?

I was not a teacher. Was I not a teacher?

I wasn’t a teacher. Wasn’t I a teacher?

The passive does not exist.

Note

The phrasal verb “used to” in the present tense is used to refer to your current habit or preoccupation.

It is used in such ways.

subject is/am/are used to v1ing (object)

I am used to working late. Am I used to working late?

I am not used to working late. Am I not used to working late? or Aren’t I used to working late?

Now this application holds for a past preoccupation, too.

Thus, there are two kinds of constructions.

I used to watch TV. (It states a regular activity in the past.)

I was used to watching TV. (It states a preoccupation in the past.)

Homework

Make a sentence using each case described above. Post your responses in a comment. I will give you feedback for free.