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: a speedometer is used for giving a driver feedback on the speed of their vehicle. 
Fact 2: Cars are vehicles and trucks are vehicles.
answer:
A driver feeds feedback on the speed of their car with a speedometer.


question:
Fact 1: plasma is formed by electrons separating from atoms in stars. 
Fact 2: Most of the matter in stars is in a plasma state.
answer:
electrons separate in stars.


question:
Fact 1: storms cause bodies of water to increase amount of water they contain. 
Fact 2: Rain increases the depth of the lakes.
answer:

storms make lake depth greater.