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: Mammalian teeth are important for digestion. 
Fact 2: For instance, bacteria in the digestive tract helps glean the most nutrients from food.
[A]: Mammalian teeth are important for gleaning nutrients from food.


[Q]: Fact 1: erosion causes a river to become deeper and wider. 
Fact 2: Erosion alters the constituents carried by water.
[A]: Deeper and wider rivers alter the constituents carried by water.


[Q]: Fact 1: fire converts chemical energy into light and heat energy. 
Fact 2: Early in human history, energy was first used by people for heating, lighting, and cooking.
[A]:
Fire converts energy into something people use for cooking.