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.
irregular
Shown is an irregular verb because shown is different to ending in -ed. Does shown end in -ed? No it doesn't end in -ed so which makes it an irregular verb.