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: shoe : untie. box : ?

A: open
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Q: candy : unwrap. letter : ?

A: open
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Q: safe : unlock. walnut : ?

A:
shell
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