What does it mean? Like in
All anybody posted on it were pictures.
********** NOT A TEACHER **********
Hello, Supernova.
(1) May I make two points?
(2) First, I think (only my opinion) that your sentence would
be easier to understand if you used that:
All that anybody posted on it were pictures.
Your sentence is basically: All were pictures.
"that anybody posted on it" describes all:
All (that anybody posted on it) / were (linking verb) / pictures.
*****
(2) Second, I think that some strict grammar books suggest that
all = the only thing.
So maybe some books would be more comfortable with:
All that anybody posted on it was pictures. =
The only thing that anybody posted on it was pictures.
Thank you