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.

[Q]: Fact 1: a flashlight requires a source of electricity to produce light. 
Fact 2: Light contains energy.
[A]: A flashlight requires a source of electricity to produce visible energy.


[Q]: Fact 1: Phylogeny is the evolutionary history of a group of related organisms. 
Fact 2: Classification can be based on phylogeny.
[A]: classification can be based in the evolutionary history of a group of related organisms.


[Q]: Fact 1: Fish have a circulatory system with a two-chambered heart. 
Fact 2: Fish have a two-chambered heart while mammals and birds have four chambered hearts.
[A]:
Mammals and fish have different circulatory systems.