A.feeding
B.digesting
C.eating
D.scraping
A.Most studies were typical and not general.
B.Most studies made a detailed study of people.
C.It's difficult to separate the use of social network from other factors.
D.There are some other factors affecting well-being.
A.how people use social network
B.whether people will get sad when they use Facebook
C.what it is about Facebook that might have negative effect
D.when people get sad during the use of Facebook