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The action of turning off the water while brushing teeth is an example of

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Which of these natural events occurs at time intervals that are the most regular?

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In the forest, one type of tree produces special seeds. These seeds start to grow only after going through a fire. In the fire, the adult trees are destroyed. Which resources, needed for growth, are now available to the newly growing seeds?

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What organ system in the human body contains the pituitary gland, hypothalamus gland, and thyroid gland?