Crossword puzzle clue "can first do it at 18"

First word across in the first-ever crossword (1913) and the first of a dozen appearances of the word in this puzzle's grid, written word search-style (left, right, down, and diagonally) ... Can you f

"Can ___? Can I? Can I?"

"Can I? Can I? Can I?" e.g.

Its first tweet was "We can neither confirm nor deny that this is our first tweet"

Director of "Can-Can."

"___ can dream, can't she?"