'Written' is the past participle of the verb 'to write'. The past tense is 'wrote'. Therefore it is an irregular verb.
yes
irregular
"Have" is an irregular verb in English.
It's irregular.
regular or irregular
It's an irregular verb.
It's an irregular verb.
To swim is an irregular verb.
It's an irregular verb.
It's an irregular verb.
Ate is an irregular verb.
By is not a verb, so it is neither regular nor irregular.