Wstaw przyimek (lub zaznacz, że go nie ma w zwrocie).

4.1 market ….. advertising
4.2 posts appear …. the news feed
4.3 we want to set ….. a forum
4.4 you can discuss … the issue
4.5 discuss the problem …. a forum
4.6 people can interact …. avatars
4.7 it’s an opportunity …. marketing
4.8 click … this word
4.9 meet ….. other players
4.10 updates ……new features