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: thirst is used to make an animal realize that it needs to replenish its bodily water by the body. 
Fact 2: Every plant and animal needs water to survive.
Example Output: thirst helps animals to survive.

Example Input: Fact 1: Birds are endothermic tetrapod vertebrates. 
Fact 2: Class Aves is for the birds, literally.
Example Output: Animals in the class aves are endothermic tetrapod vertebrates.

Example Input: Fact 1: landfills have a negative impact on the environment. 
Fact 2: Landfills are a designated place where garbage is buried underground.
Example Output:
underground garbage has a negative impact on the environment.