Q: Sentence (1) The key to solving this problem is persistence.
Sentence (2) The key to development is economic integration.. Word: key.
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A: the same meaning

Q: Sentence (1) "The quality of mercy is not strained" -- Shakespeare.
Sentence (2) While being impulsive can be great for artists, it is not a desirable quality for engineers.. Word: quality.
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A: the same meaning

Q: Sentence (1) Give that lamp a good rub and see if any genies come out.
Sentence (2) He gave the hood a quick rub.. Word: rub.
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A:
the same meaning