instruction:
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.
question:
Fact 1: Plants live just about everywhere on Earth. 
Fact 2: Most plants are producers.
answer:
producers live just about everywhere on Earth.


question:
Fact 1: a valley is formed by a river flowing. 
Fact 2: Rivers erode the rocks they flow over.
answer:
Water erodes rocks as they flow over, creating a valley.


question:
Fact 1: if an object in a fluid is more dense than that fluid then that object will sink in that fluid because of gravity. 
Fact 2: Oil is less dense than water.
answer:

water sinks in oil because of gravity.