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.

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

Example Input: Fact 1: soil is formed by rocks eroding. 
Fact 2: Soils are formed by breakdown of rock.
Example Output: rocks eroding causes them to breakdown.

Example Input: Fact 1: Differentiation is the process by which unspecialized cells become specialized. 
Fact 2: Differentiation is the specialization of a cell line.
Example Output:
specializing occurs with differentiation.