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.

Fact 1: the emission of sulfur dioxide causes acid rain. 
Fact 2: Sulfur in the coal becomes sulfur dioxide when burned.
Burning coal causes acid rain.

Fact 1: Cancer cells divide more often than normal cells, and grow out of control. 
Fact 2: Cancer is an example of a mutation in cells.
Mutation can cause growth out of control.

Fact 1: Cartilage is a tough tissue that contains a protein called collagen. 
Fact 2: Sharks have a cartilage skeleton.

Sharks have a skeleton made of tough tissue that contains a protein called collagen.