累月经年
lěi​yuè​jīng​nián

for months and years

  1. 累 lěi
    repeatedly
    (bound form) repeatedly; continuously; time and again
  2. 月 yuè noun
    month
    month; a time unit based on the cycle of the moon, twelve of which make a year; also used for monthly occurrences or payments
  3. 经 經 jīng verbpreposition
    to pass through
    to pass through; to undergo; to experience
  4. 年 nián noun
    year
    a year or the duration of a year; also used to describe annual or yearly occurrences