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: a fire requires oxygen to burn. 
Fact 2: There is no "gaseous" oxygen on the Moon and the Moon itself is bone dry.
Example Output: A fire is cannot burn naturally above the surface of the Moon.

Example Input: Fact 1: Temperature falls from lower to higher altitudes. 
Fact 2: Temperatures vary with altitude and season.
Example Output: temperatures vary depending on season.

Example Input: Fact 1: gases from burning coal and oil dissolving in water in the atmosphere causes acid rain. 
Fact 2: Acid rain is very bad and can hurt the environment.
Example Output:
Gases from burning coal and oil dissolving in water in the atmosphere can hurt the environment.