chốc chốc * ☊ 
from time to time, now and then * ☊ lâu lâu * ☊ from time to time, now and then * ☊ lúc ẩn lúc hiện * ☊ appearing and disappearing, now and then * ☊ thỉnh thoảng * ☊ from time to time, now and then, sometimes, every so often, occasionally * ☊ đôi phen * ☊ sometimes, now and then * ☊ 
now and then Temporal • frequency