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.

Input: Consider Input: Fact 1: Experiments are often done in a lab. 
Fact 2: Experiments are central to the sciences.

Output: labs are where science is done.


Input: Consider Input: Fact 1: measuring the hardness of minerals requires scratching those materials. 
Fact 2: Most gem stones are hard minerals.

Output: You can measure the hardness of a gem stone by scratching it.


Input: Consider Input: Fact 1: Earth orbiting the Sun causes seasons to change. 
Fact 2: Climate changes across seasons can be explained by the tilt of the Earth's rotation axis.


Output: The direction the earth is tilted while it orbits the sun is what causes climate to change.