رفته / نوشته / کرده

Build from the past stem. Remove the infinitive’s final ن to obtain a past stem, then add ه: دیدن → دید → دیده. This operation differs from learning an often unpredictable present stem.

Keep compounds complete. زندگی کردن → زندگی کرده; leaving only زندگی loses the participial form of the verb. Keep ordinary word boundaries between the compound’s parts.

Choose the next construction. نوشته‌ام says I have written; نوشته بودم says I had written; نوشته شد can form a passive. The same participle supports different constructions.

Adjective uses. Some participles also describe nouns, as in نامهٔ نوشته‌شده. Do not assume every participle has exactly one English adjective equivalent or that an isolated participle supplies a subject and tense.