Average time spent on smart device use per day on which the device was used in the last week
	None	1–60 min	61–120 min	121–180 min	181–240 min	Over 240 min
4.Overall	□	□	□	□	□	□
5.For study	□	□	□	□	□	□
6.For leisure	□	□	□	□	□	□