彼女がピアノをひくのが見えた。

she; her; her; girlfriend; sweetheart

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

piano

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to run somebody over (with vehicle); to knock someone down

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

to have an audience; to meet; to see; to face (an enemy); to confront; to serve (esp. as one's wife)