彼はその本に興味を示した。

he; him; his; boyfriend

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

that (something or someone distant from the speaker, close to the listener; actions of the listener, or ideas expressed or understood by the listener); the; um...; er...; uh...

book; volume; script; this; present; main; head; real; regular; counter for long cylindrical things; counter for films, TV shows, etc.; counter for goals, home runs, etc.; counter for telephone calls

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

interest (in something); curiosity (about something); zest (for)

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 (take out and) show; to demonstrate; to tell; to exemplify; to make apparent; to point out (finger, clock hand, needle, etc.); to indicate; to show; to represent; to signify; to display