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.

Q: Fact 1: most canyons are formed by flowing rivers through erosion over long periods of time. 
Fact 2: Canyon Lake Canyon lake was formed by dams on the Salt River.

A: dams can form canyons.
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Q: Fact 1: Blood pH may become unbalanced if the rate of breathing is too fast or too slow. 
Fact 2: Acidity is measured with a pH meter or with pH paper strips.

A: Blood acidity may become unbalanced if the rate of breathing is too fast or too slow.
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Q: Fact 1: Active immunity results when an immune response to a pathogen produces memory cells. 
Fact 2: Pathogens are germs that cause disease.

A:
Active immunity results when an immune response to a germ produces memory cells.
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