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: Cartilage is a tough tissue that contains a protein called collagen. 
Fact 2: Membranes attached to the cricoid cartilage .
Cricoid is a tough tissue that contains a protein called collagen.

Fact 1: electricity sometimes is used for heating buildings. 
Fact 2: Nuclear fission is the only method currently used by nuclear plants to generate electricity.
Nuclear fission can be used to heat buildings.

Fact 1: when sound reaches the ear , that sound can be heard. 
Fact 2: When the vibrations reach our ears, they are changed into sounds.

When vibrations reach our ears, they can be heard.