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: boulders are formed by glaciers melting sometimes. 
Fact 2: Glaciers are made of snow, ice and rock.

SOLUTION: boulders are formed by snow, ice, and rock melting sometimes.

PROBLEM: Fact 1: Coral reefs provide food and shelter to many ocean organisms. 
Fact 2: Oceans are important to life on Earth.

SOLUTION: coral reefs are important to earth.

PROBLEM: Fact 1: water causes refraction of light. 
Fact 2: Refraction is the bending which is caused by changing speed.

SOLUTION:
water can change the speed of light.