Verb Tense & Consistency
Verb forms place actions in time — simple past/present/future, progressive (ongoing: was walking), and perfect (completed relative to another time: had walked) — and tense should stay consistent unless the meaning requires a shift.
Perfect tenses use forms of ‘have’ plus a past participle, and irregular participles are the trap: lie/lay/lain versus lay/laid/laid, and ‘had went’ is always wrong (had gone). The past perfect marks the earlier of two past events.