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: Plants release oxygen during the day but not during the night. 
Fact 2: Plants include blue pine, hemlock, spruce and oak.

A: Blue pine releases oxygen during the day but not during the night.
****
Q: Fact 1: howling is used to warn other wolves by wolves. 
Fact 2: And somewhere a beagle howls a most pitiful sound.

A: wolves use sound to warn other wolves.
****
Q: Fact 1: Most modern gymnosperms are trees with woody trunks. 
Fact 2: Gymnosperms comprise four divisions.

A:
a living thing with four divisions can be trees with woody trunks.
****