These are the forms of the main verb that we use to construct the tenses:
|base verb||past||past participle||present participle – ing|
do + base verb
(except future: will + base verb)
|+||She did swim.
|She does swim.
|She will swim.|
|–||She didn’t swim.||She does not swim.||She will not swim.|
|?||Did she swim?||Do you swim?||Will you swim?|
have + past participle
|+||I had swum.||I have swum.||I will have swum.|
|–||She had not swum.||She has not swum.||She will not have swum.|
|?||Had she swum?||Has she swum?||Will she have swum?|
be + ing
|+||She was swimming.||She is swimming.||She will be swimming.|
|–||She was not swimming.||She is not swimming.||She will not be swimming.|
|?||Was she swimming?||Is she swimming?||Will she be swimming?|
have been + –ing
|+||She had been swimming.||She has been swimming.||She will have been swimming.|
|–||She had not been swimming.||She has not been swimming.||She will not have been swimming.|
|?||Had she been swimming?||Has she been swimming?||Will she have been swimming?|
The difference between regular and irregular verb tenses is that regular verbs, such as play are always the same.
play, played, playing
Irregular verbs such as sing use different words all together to refer to tense.
sing, sang, sung, singing.