Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
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Question: Fact 1: soil is formed by rocks eroding. 
Fact 2: Soils are formed by breakdown of rock.

Answer: rocks eroding causes them to breakdown.


Question: Fact 1: microorganisms cause food to spoil. 
Fact 2: Food poisoning occurs when spoiled food is eaten.

Answer: Microorganisms cause food poisoning.


Question: Fact 1: Hair is a fiber that is found only in mammals. 
Fact 2: Bats have hair like all mammals so they can stay warm.

Answer:
fibers on mammals keep them warm.