qua thời gian 
for a long (period of) time [ qua ] : after, by, through, over; last (week, day, etc.); to pass by, go across, cross over
[ thời ] : time(s), era
[ gian ] : (1) dishonest, underhanded, tricky; (2) apartment, room; (3) difficult, hard; (4) danger, peril
Most Common Compounds Set 1:
Most Common Compounds Set 2 :