Obviously the subset of occupied cells is not the same at different times.

But only when there is real mixing and an occupied cell is found do we ask which kind of molecule is there.

For some reason Fred had seen fit to put another on a stool near the one occupied cell.

The mouse didn't go into either of the occupied cells; only the empties.

And she never led him past an occupied cell.

His was the only occupied cell in the entire block.

At last she passed two occupied cells, their inhabitants shrouded in shadows.

The turnkey pondered a moment and then jerked his thumb toward the occupied cell.

Otherwise, you can choose between the occupied cells, where the character will find the occupant between himself and the cell door.

He began to search far and wide with his doodlebug until he located the other occupied cells.