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: Mammals conserve body heat with their hair or fur. 
Fact 2: Mammals Hair or fur covers the bodies of most mammals.
Example Output: Mammals conserve body heat with their fuzzy, protective covering.

Example Input: Fact 1: energy is used for heating a building by a heating system. 
Fact 2: Energy used for heating is the single most commonly used form of energy worldwide.
Example Output: Heating buildings is a very common production of energy worldwide.

Example Input: Fact 1: most canyons are formed by flowing rivers through erosion over long periods of time. 
Fact 2: Most river erosion occurs when the river is in flood.
Example Output:
Most canyons are formed when rivers are in flood.