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: Viruses cannot reproduce by themselves. 
Fact 2: Passwords multiply and reproduce amongst themselves.
Viruses cannot multiply by themselves.

Fact 1: Insects may live in large colonies and have complex social behaviors. 
Fact 2: Ants and butterflies are insects.
ants may live in large colonies.

Fact 1: the vanes rotating in an electric fan causes air to move. 
Fact 2: Output of the fan is varied by means of a series of adjustable vanes upstream of the impeller.

by adjustable rotating in an electric fan air output of the fan is varied.