Problem: Given the question: What is the missing first step of the following process:  -  Two types of proteins exist in filaments in the muscles - The filaments move when the brain instructs them to - The motion of the filaments cause the muscle to shorten and contract - Opposing pairs of muscles exist in order to provide the necessary range of motion.
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The answer is:
Electrical signals in the brain travel through nerves to muscles


Problem: Given the question: What is the missing first step of the following process:  -  The aluminum is collected - Taken to a treatment plant - The aluminum is sorted and cleaned ready for reprocessing - The aluminum is re-melted - Turned into molten aluminum - The aluminum is made into large blocks called ingots - The ingots are sent to mills to be rolled out - The rolled out product is made into new aluminum products.
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The answer is:
The consumer throws aluminum cans and foil into a recycle bin


Problem: Given the question: What is the missing first step of the following process:  -  The earth changes energy from the sun into heat - Heat rises from the ground - Greenhouse gas molecules in the atmosphere prevent the heat from going into space - The temperature of the earth increases - The temperature continues to rise and melts the polar ice caps - The temperature rises even faster.
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The answer is:
