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.

Fact 1: Brain cells die quickly if their oxygen supply is cut off. 
Fact 2: Without proper brain functioning the body dies.
without oxygen the body dies.

Fact 1: Viruses cause many human diseases. 
Fact 2: Human viruses are created by natural process.
Something created by a natural process  cause many human diseases.

Fact 1: Many plants respond to the days growing shorter in the fall by going dormant. 
Fact 2: Many plants are in a dormant state in winter.

some plants are dormant when the days are shorter.