彼は警察を見ると走った。

he; him; his; boyfriend

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

police; police officer; police station

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 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...

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

to run; to travel (movement of vehicles); to drive; to hurry to; to retreat (from battle); to take flight; to run away from home; to elope; to tend heavily toward