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: Humans have collected and grown mushrooms for food for thousands of years. 
Fact 2: Foods rich in chlorine are mushrooms, parsley, sweet potato, rhubarb, and especially tomato.
[A]: Humans have collected and grown foods rich in chlorine for thousands of years.


[Q]: Fact 1: Viruses are not cells at all, so they are neither prokaryotes nor eukaryotes. 
Fact 2: Viruses Viruses are the smallest agents of disease.
[A]: The smallest agents of disease are not cells at all, so they are neither prokaryotes nor eukaryotes.


[Q]: Fact 1: a switch is used to start the flow of current in an electrical circuit. 
Fact 2: If the switch is open, electricity flows, and the light is on.
[A]:
A light turns on when the switch is open so the current can flow.