Tenses review - present perfect/past perfect simple
Present Perfect (has/have + 3rd form)- action still going on (started in the past up to now)/action recently finished & result still visible -when is NOT important/mentioned - signal words: so far, since, up till now, how long, ever, never, yet, still etc.
difference with Present Perferct Continuous: Present Perfect -> shorter actions, also with "never
Past Perfect (had + 3rd form) - action took place before another action in the past (always accompanied with a verb in the past simple in the sentence) - signal words: before, after, when