Problem: What is the missing first step of the following process: - Once in the lungs, oxygen is moved into the bloodstream and carried through your body - At each cell in your body, oxygen is exchanged for a waste gas called carbon dioxide - Your bloodstream then carries this waste gas back to the lungs where it is removed from the blood stream and then exhaled - Your lungs and respiratory system automatically perform this vital process, called gas exchange -

A: He air we breathe contains oxygen and other gases

Problem: Given the question: 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.
++++++++++++++++++++++++++++++++
The answer is:
Limestone is located under the soil

input question: What is the missing first step of the following process: - The pollution negatively affects the water quality - The pollution negatively affects the health of plants and animals - The plants and animals have shorter, less healthy lives - The plants and animals do not reproduce very well - The number of plants and animals decreases over time - The quality of water gets worse and worse as there are no plants or animals to clean it - Eventually there is nothing living in the water and it is unusable -???
output answer: Pollution enters natural water sources such as rivers and lakes

What is the missing first step of the following process: - The bird collects bits of sticks and grass - The sticks and grasses are placed between support branches - Leaves, mud and spider webs are added to the sticks - The mud, leaves and webs glue the sticks together - The solid nest supports the eggs -
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Answer: A bird picks a spot high spot, often in a tree

Q: What is the missing first step of the following process: - The boiler produces steam under high pressure - The steam generated in the boiler flows down into a cylinder - Just ahead of the wheels, pushing a tight-fitting plunger, the piston - The piston is connected to one or more of the locomotive's wheels through a kind of arm-elbow-shoulder joint called a crank and connecting rod - As the piston pushes, the crank and connecting rod turn the locomotive's wheels and power the train along - An outlet valve opens and the piston pushes the steam back through the cylinder and out up the locomotive's chimney -
A: Coal is loaded into the firebox

[Q]: What is the missing first step of the following process: - The energy from the sunlight causes an enzyme in the plant to break apart the water - The water breakes into oxygen, hydrogen, and electrons - Hydrogen, along with electrons energized by light, converts NADP into NADPH - Oxygen diffuses out of the plant as a waste product of photosynthesis -
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[A]:
Sunlight hits chloroplasts in the plant