TASK DEFINITION: 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.
PROBLEM: Fact 1: treating water is used to remove harmful substances before drinking. 
Fact 2: Chlorine is also used to treat water.

SOLUTION: Chlorine is also used to remove harmful substances from water before drinking.

PROBLEM: Fact 1: completing a circuit causes electricity to flow through that circuit. 
Fact 2: Electricity can give the opener a shock.

SOLUTION: completing a circuit can give someone a shock.

PROBLEM: Fact 1: natural disasters can cause animals to leave an environment. 
Fact 2: Flooding is the most common natural disaster.

SOLUTION:
Flooding can cause animals to leave an environment.