1. The present perfect tense is used to talk about experiences that have occurred at unspecified times in the past. It is used to discuss actions that began in the past and continue in the present, or that have results in the present.
2. The present perfect tense is formed using the auxiliary verb "have" and the past participle of the main verb. It is used with time expressions like "never," "ever," "since," and "for."
3. Questions in the present perfect can be formed to ask about experiences, durations of time, numbers of occurrences, or locations.