How can I tell what the past participle of something is- especially if the past participle is usually different? Ex: Drink = have drunk, choose = had chosen, and bring = have brought. If these are all past participles, how can I know how to figure out the past participles of other words?
Cambridge Dictionary gives the participle under the verb definition, if it is irregular. The verb "dig" is irregular, and the participle, "dug" is shown. By contrast, "look" is a regular verb and so no participle is shown, indicating that you form the participle in the normal way. Oxford does not do this in its verb definitions, but has a handy page summarising the formation of regular verb present and past tenses and participles, and a list of common irregular verbs.