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: pesticides can cause pollution. 
Fact 2: Air pollution harms the ecosystem.

A: pesticides can harm the ecosystem.
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Q: Fact 1: Insects may live in large colonies and have complex social behaviors. 
Fact 2: Some Beetles Co-exist in Other Insect Colonies.

A: some beetles have complex social behaviors.
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Q: Fact 1: fluoride decreases tooth decay. 
Fact 2: Tooth decay is a destruction of the tooth enamel.

A:
Flouride prevents the destruction of tooth enamel.
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