Smartphone, while usefue, present serious problem. In this essay, I'll talk about the harmful effects of
while usefue=even though smartphone is useful，the present serious problem...
According to a survey by the American Psychological Association，“People .......”(Bubb 2017)
写作中一般用：In sum,In summary
To sum up(more in meeting)
Chicago Manual of style( for booke,novels,)
The Associated Press style guide(newspaper)
MLA style guide(the Modern Language Association style guide)(for humanities)