canh chừng 
observation, surveillance; to (keep) watch, observe [ canh ] : (1) soup; (2) to guard, watch over; (3) to plow; (4) to change, alter; (5) 7th cycle of the twelve years of the Chinese zodiac
[ chừng ] : about, approximately; rough measure, rough extent, rough estimate
Most Common Compounds Set 1:
Most Common Compounds Set 2 :