[Q]: What is the missing first step of the following process: - Is exposed to air - A chemical reaction occurs - The iron starts to oxidize - The iron starts to rust.
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[A]: Iron is exposed to oxygen

input: Please answer the following: What is the missing first step of the following process: - Over long periods of time rain can hit the limestone - And cause a acidic reaction - The limestone will slowly disintegrate - A large gap with be where the limestone was - Result in the cave.
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output: Some of the rock in the ground is made of limestone

Please answer this: What is the missing first step of the following process: - The oxygen travels into the lungs - The oxygen binds to hemoglobin proteins within erythrocytes (red blood cells) - The erythrocytes are pumped through the body by the heart - All cells receive the oxygen.
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Answer: Oxygen enters the body through the mouth or nose

Problem: What is the missing first step of the following process: - The receptors will lock onto a target cell using these chemical receptors on the surface, which docks onto the cell surface - The receptors then go into the cell - The receptors use it like a factory - The receptors take it over and make it produce thousands or in some cases millions of copies of new viruses - The copies come streaming out of the cell - The copies infect other cells to make more viruses, or they escape from the body and infect a new victim -

A: The flu virus has receptors, which are like viral Velcro, on the surface of the virus particle

Problem: Given the question: What is the missing first step of the following process: - Water is put in pipes in the coal-fired steam station - The coal is crushed - The coal is moved into a boiler along with hot air - The water is moving through pipes in the boiler - The steam from the water is blown against a turning mechanism - The force of the steam makes the mechanism turn - The mechanism generates electricity.
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The answer is:
Coal is put in a coal-fired steam station

Problem: What is the missing first step of the following process: - Causes them to absorb aluminum from soil - The water runs off from the soil into lakes, streams, etc - Fish and their eggs die - Frogs and plants die - Insects and other wildlife die - The ecosystem is out of balance, causing further problems -

A:
Acid rain makes waters acidic