input: Please answer the following: What is the missing first step of the following process: - Rain picks up carbon dioxide as it falls to earth - The rain falls on the soil over the limestone - The carbon dioxide in the rain washes through the soil - The carbon dioxide turns into acid - The acid in the rain gets to the limestone below the soil - The acid dissolves the limestone - Acid continues to erode the limestone with more rain over time - The eroded limestone sometimes forms caves.
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output: Limestone is located under the soil

input: Please answer the following: What is the missing first step of the following process: - Air enters bronchioles - Bronchioles have tiny air sacs called alveoli - Alveoli surrounded by small blood vessels - Oxygen absorbed by small blood vessels - Vessels deliver oxygen to every cell in the body - Blood brings carbon dioxide back to lungs - Carbon dioxide released when you exhale.
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output: Air enters the lungs through bronchial tubes

input: Please answer the following: What is the missing first step of the following process: - The oil is transported to stores - Oil is purchased by homeowners - Oil is placed into a stove in the house - The oil is lit on fire, and burns for a long time - The warm air off of the oil travels through the house -
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output: Oil is gathered through mining operations

input: Please answer the following: What is the missing first step of the following process: - Food is squeezed down the esophagus when you swallow - Acid and enzyme in the stomach break the food down - Releases nutrients - Food then pumped into small intestine - Fluid and enzymes from liver and pancreas pumped into small intestine - Help break food into smallest molecules - Nutrients pass through wall of small intestine - Nutrients absorbed into blood stream - Unused materials passed into large intestine to become fecal matter.
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output:
An enzyme in saliva begins to break down carbohydrates