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: Muscle contraction occurs when muscle fibers get shorter. 
Fact 2: Isometric exercise is a sustained contraction of large muscles, such as weight lifting.
Example Output: Weight lifting requires  shortening of of the fibers of large muscles.

Example Input: Fact 1: if a tree falls then sunlight becomes available to the surrounding plants. 
Fact 2: When a big tree falls, sunlight shines on smaller plants and they get a chance to grow.
Example Output: Plants grow better when surrounding trees fall.

Example Input: Fact 1: smoking causes direct damage to the lungs. 
Fact 2: When lung damage is experienced, frequently the total capacity of the respiratory system is reduced.
Example Output:
Smoking can reduce respiratory system capacity.