input: Please answer the following: What is the missing first step of the following process: - Waste enters the kidneys - A processing moment in the kidneys let waste and fluid pass - Prevents larger molecules to pass - Fluid goes back to the bloodstream - Bad waste is removed - The final product is turned into urine.
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output: Fluid

input: Please answer the following: What is the missing first step of the following process: - Aluminum flows into streams and lakes - Acid rain dissolves minerals and nutrients in soil - Washes them away so plants can't benefit from them - PH in soil and water gets affected which can kill plants and animals - Acid rain in fog at higher elevations can strip foliage off trees.
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output: Acid rain leaches aluminum from clay particles in soil

input: Please answer the following: What is the missing first step of the following process: - After a rain, water seeps into cracks and pores of soil and rock - The water percolates beneath the land surface - Some of the water reaches a zone where all the cracks and pores in the rock are already filled with water - Rainwater absorbs some carbon dioxide as it passes through the atmosphere and even more as it drains through soil and decaying vegetation - The water combines chemically with the carbon dioxide - A weak carbonic acid solution is formed - This acid slowly dissolves calcite, forms solution cavities, and excavates passageways -
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output: Solution caves are formed in limestone and similar rocks by the action of water

input: Please answer the following: What is the missing first step of the following process: - The owl flys out into the night - The owl looks down at the ground - The owls keen eyesight allows him to see in the dark - The owls sensitive hearing allows him to locate hidden prey - The owl swoops down - The owl catches a mouse in his talons.
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output:
An owl leaves his nest