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.

Q: backpack : unzip. shoe : ?

A: untie
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Q: suitcase : open. safe : ?

A: unlock
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Q: letter : open. peas : ?

A:
shell
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