Those actions, which is both good and bad outcomes are together. Both can cause stress from working or studying but it will jeopardize the eyes to watch out for handheld screens for a long time.
Those actions, which are both good and bad coexist. It can relieve stress from work or school. But it would be better for the eyes to glare screen mobile for a long time.
The action they have both advantages and disadvantages together. Both can make the stress from work or school. But it is bad for eyes to stare at the screen mobile phone for a long time.