Take a look at the sentence again:
Mauricio would have _________ the seven-foot wave into shore if a huge shark
had not been patrolling the waters underneath the surfboard, hoping for
a dangling arm or leg.
The sentence requires the past participle of ride, an irregular verb. Ridden is the past participle form.
| Verb | Simple Present | Simple Past | Past Participle |
| ride | ride(s) | rode | ridden |
Rode, the form you chose, is the simple past. You cannot use the simple past if you have auxiliary verbs like would and have. Before you continue, review the rules for irregular verbs.
Try again to escape Grammar Hell!