instruction:
Two analogies on manipulating items in a kitchen is given in the form "A : B. C : ?". The phrase "A : B" relates item A to its appropriate manipulation B. Your task is to replace the question mark (?) with the appropriate manipulation of item C, following the "A : B" relation. Your answer should be a verb which shows a way to manipulate the given object.
question:
peas : shell. backpack : ?
answer:
unzip


question:
letter : open. backpack : ?
answer:
unzip


question:
letter : open. shoe : ?
answer:

untie