"Bottle 2"

use full-length room descriptions.

Start Room is a room.
"Once again you are in the exitless Start Room.".

a closed openable transparent container called a bottle is in Start Room.

the description of the bottle is
"[if the cap is screwed]A closed bottle that has a cap screwed on it.
[otherwise] An uncapped open bottle. [end if]".

a thing called a cap is part of the bottle.
understand "bottle cap" as the cap.
the cap can be either screwed or unscrewed.
the cap is screwed.
the description of the cap is 
"[if screwed] The cap is currently screwed to the bottle.
[otherwise] A cap that can be screwed or unscrewed.[end if]".

understand the command "screw" or "turn" as something new.
understand the command "unscrew" as something new.

screwing is an action applying to one thing.
unscrewing is an action applying to one thing.

understand "screw [something]" or "turn [something]" as screwing.
understand "unscrew [something]" as unscrewing.

instead of unscrewing the cap when the cap is screwed:
now the cap is unscrewed;
now the bottle is open;
move the cap to the player;
say "You unscrew the cap from the bottle and have it in your hands.".

instead of screwing the cap when the cap is unscrewed:
now the cap is screwed;
now the bottle is closed;
now the cap is part of the bottle;
say "You screw the cap back onto the bottle.".

instead of screwing the cap when the cap is screwed:
say "the cap is already screwed on the bottle.".

instead of unscrewing the cap when the cap is unscrewed:
say "The cap is already unscrewed.".

instead of screwing the cap when the cap is unscrewed:
now the cap is screwed;
now the cap is part of the bottle;
now the bottle is closed;
say "You screw the cap back onto the bottle.".

instead of unscrewing the cap when the cap is screwed:
now the cap is unscrewed;
move the cap to the player;
now the bottle is open;
say "You unscrew the cap from the bottle.".

screwing it to is an action applying to two things.
understand "screw [cap] to [bottle]" as screwing it to.
understand "screw [cap] on [bottle]" as screwing it to.

unscrewing it from is an action applying to two things.
understand "unscrew [cap] from [bottle]" as unscrewing it from. 
understand "remove [cap]  from [bottle]" as unscrewing it from. 

taking it from is an action applying to two things.
understand "take [cap] from [bottle]" as taking it from. 

instead of taking the cap from the bottle when the cap is unscrewed:
say "You've already got it.".

instead of taking the cap from the bottle when the cap is screwed:
now the cap is unscrewed;
move the cap to the player;
now the bottle is open;
say "You unscrew the cap from the bottle.".

instead of unscrewing the cap from the bottle: 
now the cap is unscrewed;
now the bottle is open;
move the cap to the player;
say "You unscrew the cap from the bottle and have it in your hands.".

instead of screwing the cap to the bottle:
now the cap is screwed;
now the cap is part of the bottle;
now the bottle is closed;
say "You screw the cap back onto the bottle.".

instead of opening the bottle when the bottle is closed,
try unscrewing the cap from the bottle.

instead of opening the bottle when the bottle is open,
say "the bottle is already open.".

instead of closing the bottle when the bottle is open,
try screwing the cap to the bottle.

instead of closing the bottle when the bottle is closed,
say "the bottle is already closed."

instead of dropping the cap when the cap is unscrewed:
move the cap to the location;
say "You drop the cap on the floor.".

instead of taking the cap when the cap is in the player:
say "You've already got it. ".

instead of taking the cap when the cap is part of the bottle:
now the cap is unscrewed;
now the cap is in the player;
now the bottle is open;
say "You unscrew the cap from the bottle.".

instead of putting the cap on the bottle when the cap is unscrewed:
now the cap is on the bottle;
try screwing the cap to the bottle.

instead of putting the cap on the bottle when the cap is screwed,
say "You've already screwed the cap back on the bottle!".