[Q]: What is the missing first step of the following process: - The fertilized egg, now a zygote, travels to the uterus - The zygote implants in the uterus - The zygote becomes an embryo - The embryo becomes a fetus - The fetus grows for approximately 9 months - The woman gives birth to a baby - The baby grows into a child - The child becomes an adult - The adult mates with another adult -
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[A]: A sperm and egg meet inside a woman's fallopian tube

[Q]: What is the missing first step of the following process: - The virus has receptors that lock onto a target cell - The virus enters the cell - The virus uses the cell like a factory to make new copies of the virus - The new copies of the virus leave the cell - Infect other cells - The host gets sick as its cells are damaged.
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[A]: A virus enters a host body

[Q]: What is the missing first step of the following process: - The water combines with carbon dioxide in the air to form carbonic acid - As the acid is formed, the iron starts to dissolve - Some of the water breaks down into hydrogen and oxygen - The free oxygen and dissolved iron bond together - They form iron oxide, which is rust -
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[A]: Water comes into contact with something made of iron

[Q]: What is the missing first step of the following process: - The sediments become glued together - The glued together parts become hard like cement - The sediment becomes a big rock - The rocks erode slowly - The rocks come apart - The rocks become smaller rocks - The rocks continue to erode into smaller rocks - The process starts again.
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[A]:
Minerals fill spaces between bits of sediment