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.

[Q]: Fact 1: Plasma cells are activated B cells that secrete antibodies. 
Fact 2: Antibodies are produced by plasma cells.
[A]: activated B cells secrete antibodies.


[Q]: Fact 1: dew is formed when water vapor condenses over night. 
Fact 2: Dew begins to evaporate when the temperature reaches the dew point.
[A]: condensed water vapor evaporates at certain temperatures.


[Q]: Fact 1: a compass is used to navigate oceans. 
Fact 2: Map navigators tend to use Grid North, or Magnetic north as as default.
[A]:
A compass is used to find magnetic north.