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: detailed observation of celestial objects requires a telescope. 
Fact 2: Telescopes Telescopes Telescopes and microscopes both use two lenses to produce magnified images.

SOLUTION: Two lenses to produce magnified images allow for detailed observation of celestial objects.

PROBLEM: Fact 1: condensation causes clouds to form. 
Fact 2: Fog is a cloud that forms on the ground.

SOLUTION: condensation causes fog.

PROBLEM: Fact 1: tectonic plates being pushed together causes earthquakes. 
Fact 2: Plate tectonics states that the Earth's plates are constantly moving.

SOLUTION:
the Earth constantly moving then being pushed together causes earthquakes.