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: skin is used for breathing air by frogs. 
Fact 2: Air contains oxygen.
Example Output: skin is used for breathing oxygen by frogs.

Example Input: Fact 1: skin is used for protecting the body from harmful substances. 
Fact 2: Contamination is the unintended presence of harmful substances or microorganisms in food.
Example Output: The skin is used for protecting the body from contamination.

Example Input: Fact 1: Menopause occurs when menstruation stops occurring, usually in middle adulthood. 
Fact 2: By definition, menopause occurs when menstruation stops permanently.
Example Output:
Usually in middle adulthood menopause happens when menstruation stops permanently.