The reader who has spent serious effort on a problem may ________ from the effort even if he doesn't succeed in solving the problem．

1. A.
   come
2. B.
   benefit
3. C.
   conclude
4. D.
   judge

The reader who has spent serious effort on a problem may________ from the effort even if he does not succeed in solving the problem．

1. A.
   benefit
2. B.
   conclude
3. C.
   derive
4. D.
   deviate

The reader who has spent serious effort on a problem may________ from the effort even if he does not succeed in solving the problem．

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