on and off：斷斷續續的，（船）時而靠岸時而離岸。
For 5 years on and off she worked on
Desk Murder, finishing the painting in
2015.
這幅作品，她斷斷續續地畫了5年，才於2015年完成。
Mike was turning the TV set on and off.
邁克正在斷斷續續地開關著電視機。
It rained on and off all day.
雨斷斷續續地下了一整天。
I shall sit here,he said, "on and off, for
days and days."
「我將坐在這兒」，他說，「斷斷續續地坐上好幾天。