instruction:
Two analogies that relate actions to the tools used to perform the action is given in the form "A : B. C : ?". "A : B" relates action A to tool B. Your task is to replace the question mark (?) with the appropriate tool for the given action C, following the "A : B" relation.
question:
cut : glass. spread : ?
answer:
knife


question:
wash : rag. unlock : ?
answer:
key


question:
unlock : key. scrub : ?
answer:

brush