Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Sensory organs such as the eyes contain cells called sensory receptors that respond to particular sensory stimuli. Answer: sensory receptors

Answer: Sensory organs that respond to particular sensory stimuli contain cells called what?

Question: Passage: The problem doesn't stop with plowing. Crops are usually planted in rows, with bare soil in between the rows. In places where crops grow only during part of the year, the land may be bare for a few months. Answer: months

Answer: In places where crops grow only during part of the year, the land may be bare for a few?

Question: Passage: Metalloids such as boron have an outer energy level that is about half full. These elements need to gain or lose too many electrons for a full outer energy level to come about easily. As a result, these elements are not very reactive. They may be able to conduct electricity but not very well. Answer: half full

Answer:
About how full is the outer energy level in metalloids?