What is the complete verb of sentence have you ever ridden a horse before?

The complete verb in the sentence "Have you ever ridden a horse before?" is "have ridden".

Here's why:

* Have: This is the auxiliary verb (helping verb) that helps form the present perfect tense.

* Ridden: This is the past participle of the verb "ride", which combines with "have" to form the present perfect tense.

The complete verb is the combination of these two words.