Welp, I should admit that I use smartphone too much. When I feel tired, I often lay on the bed and on the phone. 

Besides, some apps (for example Zhihu) limit the function of website verison and I have to download App, which causes the increase of smartphone using time.

Thanks to the principal @圓環之理 for giving this discuss a top-fixed.

回復 @圓環之理：Thank you very much.