彼がジーンズを履いているのを見た事が無い。

he; him; his; boyfriend

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

jeans

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 put on (or wear) lower-body clothing (i.e. pants, skirt, etc.); to put on (or wear) footwear; to affix a sword to one's hip; to affix a bowstring to a bow

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 see; to look; to watch; to view; to observe; to look over; to look on; to assess; to examine; to judge; to look after; to keep an eye on; to take care of; to view (e.g. flowers, movie); to try; to try out; to see that...; to find that...

thing; matter; incident; occurrence; event; something serious; trouble; crisis; circumstances; situation; state of affairs; work; business; affair; after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to; nominalizing suffix; pretending to ...; playing make-believe ...; alias; aka; nickname; alternative name; also known as

nonexistent; not being (there); unpossessed; unowned; not had; unique; indicates negation, inexperience, unnecessariness or impossibility; not ...; to not be...; to have not ...