Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: The two materials do have at least one thing in common. The atoms in the materials are held together by covalent bonds. These bonds consist of electrons shared between two or more atoms. Unlike ionic bonds, where electrons are either lost or gained by an atom to form charged ions, electrons in covalent compounds are shared between the two atoms, giving rise to properties that are quite different from those seen in ionic materials. Answer: ionic bonds

Answer: Electrons in covalent compounds are shared between the two atoms, unlike the case in what type of bonds?

Question: Passage: An anticline is a fold that arches upward. The rocks dip away from the center of the fold ( Figure below ). The oldest rocks are found at the center of an anticline. The youngest rocks are draped over them at the top of the structure. When upward folding rocks form a circular structure, that structure is called a dome . If the top of the dome is eroded off, the oldest rocks are exposed at the center. Answer: anticline

Answer: What is the term for a fold that arches upward?

Question: Passage: Water power does not burn a fuel. So it causes less pollution than many other kinds of energy. Water power is also a renewable resource. Water keeps flowing downhill. Although we use some of the energy from this movement, we are not using up the water. Answer: renewable

Answer:
What type of resource is water power?