Some athletes have taken drug tests to prove they are not on steroids. does this sentence contain a regular or irreagular verb, and why?

Answer 1

That sentence has two irregular verbs.

Regular verbs form their past tense and past participles by adding -ed. Examples of regular verbs:

jump, jumped, have jumped
paint, painted, have painted
listen, listened, have listened

But, irregular verbs form their past tense and past participles in other ways.

Examples of irregular verbs:

come, came, have come
swim, swam, have swum
take, took, have taken
drink, drank, have drunk
do, did, have done
to be (is, are) was, were, have been
run, ran, have run