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: a sifter is used for separating mixtures. 
Fact 2: For the seasoning mixture combine all ingredients.
a sifter is used for separating combined ingredients.

Fact 1: if an object reflects light toward the eye then that object can be seen. 
Fact 2: Light is made up of particles called photons.
If an object reflects photons toward the eye then that object can be seen.

Fact 1: Viruses are so small that they can be seen only with an electron microscope. 
Fact 2: Where most viruses are DNA, HIV is an RNA virus.

HIV is so small it can only be seen with an electron microscope.