You need to answer a given question containing a blank (_). Your answer must be one of the two objects mentioned in the question, for example "trophy" and "suitcase". Your answer must not contain a word that is not present in the question. Please don't use articles (e.g., the, a) before the answer.
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Question: Steven's teacher made him redo the homework assignment, because he had failed to understand the _ .

Answer: assignment


Question: The chocolate could not be sliced with the knife because the _ it too blunt.

Answer: knife


Question: Mark choosed to do his morning run on the road instead of the forest, because the surface in the _ is smoother.

Answer:
road