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: Some parasites kill their host, but most do not. 
Fact 2: Tapeworms are internal parasites of vertebrates.

A: most tapeworms do not kill their host.
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Q: Fact 1: Light enters the eye through an opening called the pupil. 
Fact 2: Just behind the pupil is a lens.

A: light enters the eye through an opening just in front of the lens.
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Q: Fact 1: a airplane is used for moving people across bodies of water. 
Fact 2: Millions of people fly safely in airplanes every year.

A:
Airplanes transport millions of humans move across bodies of water every year.
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