What is the present and past form of did?

The word "did" is already in the past tense. It is the past tense of the verb "do".

There isn't a present tense form of "did." Instead, the present tense forms of "do" are:

* do (present tense, singular and plural)

* does (present tense, third person singular)

For example:

* Present tense: I do my homework every day. / She does her homework every day.

* Past tense: I did my homework yesterday. / She did her homework yesterday.