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: Nephrons are the structural and functional units of the kidneys. 
Fact 2: Finally, the fluid in the nephron reaches a collecting duct .
[A]: fluid in the kidneys collect into ducts.


[Q]: Fact 1: Cells cannot survive without oxygen. 
Fact 2: Life is responsible for oxygen in the atmosphere.
[A]: cells cannot survive without the atmosphere.


[Q]: Fact 1: most canyons are formed by flowing rivers through erosion over long periods of time. 
Fact 2: Rivers flow downhill due to gravity.
[A]:
most canyons are formed due to gravity through erosion.