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: Viruses are not cells at all, so they are neither prokaryotes nor eukaryotes. 
Fact 2: Viruses Viruses are the smallest agents of disease.

Answer: The smallest agents of disease are not cells at all, so they are neither prokaryotes nor eukaryotes.


Question: Fact 1: Marine species live mainly in shallow coastal waters. 
Fact 2: And a marine geologist does the same, but in the water.

Answer:
Water species live mainly in shallow coastal waters.