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.

Example Input: Fact 1: treating water is used to remove harmful substances before drinking. 
Fact 2: Chlorine is also used to treat water.
Example Output: Chlorine is also used to remove harmful substances from water before drinking.

Example Input: Fact 1: hitting an object causes the particles in that object to vibrate. 
Fact 2: Sounds are caused by vibrations.
Example Output: hitting an object causes Sounds.

Example Input: Fact 1: a switch is used to start the flow of current in an electrical circuit. 
Fact 2: Electrical power including lights etc can then be switched on.
Example Output:
lights are on when there is flow of current in an electrical circuit.