!! used as default html header if there is none in the selected theme.
The server will give you the graph of a function f (x), whose expression will be hidden. You will then be presented a certain number of other graphs, corresponding to modifications of f (x) such as f (|x|), |f (x)|, or even |f (x)|+1, etc (see the menu below). And you should cocate the one which corresponds to one which will be precised in a question. To give the reply, you can simply click on the graph which you believe to be the good one.