buy the food / Megan / +
Megan has already bought the food.
make a cake / Megan / +
Megan has already made a cake.
plan the games / Tim / +
Tim has already planned the games.
clean up / Megan and Tim / -
Megan and Tim haven't cleaned up yet.
invite their friends / Megan and Tim / +
Megan and Tim have already invited their friends.
cook the food / Tim / -
Tim hasn't cooked the food yet.
decorate the room / Megan / -
Megan hasn't decorated the room yet.
choose the music / Megan / -
Megan hasn't chosen the music yet.