長い年月が過ぎた。

long (distance); long (time); lengthy

months and years

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

to pass through; to pass by; to go beyond; to pass (i.e. of time); to elapse; to have expired; to have ended; to be over; to exceed; to surpass; to be above; to be no more than ...; to be excessive; to be too much; to be too ...