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 black hole is formed by a high-mass star collapses. 
Fact 2: Fundamentally, a black hole is invisible.
Example Output: a star collapsing can be invisible.

Example Input: Fact 1: Lions live in social groups called prides. 
Fact 2: Leo's symbol is the lion.
Example Output: Leo's symbols live in social groups called prides.

Example Input: Fact 1: Mammals have a layer of fat under the skin to help insulate the body. 
Fact 2: Pugs are mammals and mammals shed.
Example Output:
pugs have a layer of fat under the skin.